3D Printing a More Tangible Idea


Why write another article about 3D printing?

The internet already offers an abundance of information on the subject. Mountains, in fact.

Everyone has been talking and writing about it. It seems like every other week there’s a new research program, a new project and a new supplier emerging. Also, democratized developments like RepRap and its spin-off’s have built a vast knowledge base in the peer production realm. All True.

But there may be more to be said…


These days we can print out 3D objects in plastic, metal, ceramics and even organic material. We can print in just about any shape we can imagine.

All this suggests that we will soon be able to print out trains, planes, automobiles and even complex body parts. We also hear claims like; “We will print our own phones” and “Conventional manufacturing techniques will soon be rendered obsolete”.

3D printing is the holy grail to manufacturing and the distribution of products.

Well…yes and no.

Talk is cheap and the web has a way of taking that to the next level. The internet flattens things out. Sure, truth has a way of eventually rising above it all. Only the most robust of ideas will move up through the ranks and prevail. Moving from perception to proof is what brings value to something. It, at the very least, makes it more reasonable and tangible to talk about.

But that process takes time.

In the mean time how does one separate what is real from what is rumor or just plain wrong?

Conceptually, 3D printing can produce anything. But at this stage the technology presents the ability to print out the shape of an object. It can do this in a certain material and within certain accuracy. By itself that’s incredible. And, for many types of products that may be enough to get the job done. Yet, for most, there is typically a lot more involved in the manufacturing and production of functional products. The Star Trek replicator?

Not just yet. 

Engines of Revolution

Labeled with words like “disruptive” and “revolution”, additive manufacturing, or 3D printing technologies as they are referred to these days, are actually not that new. The concept is old, very old. In fact, many of the patents related to the latest core technologies over the past 25 years have expired or will soon expire.

What is actually new here is the recent accessibility of these technologies to the masses. At least to some level. Specifically, low cost 3D printers for home use and 3D print service providers. You can now own your own 3D printer. You can also use a 3D print service provider which can provide the latest and greatest technologies without having to actually own a high-end and costly machine.

The impact of 3D printing on industry is undeniable. Then again…just as it was more than 25 years ago. But the revolution? Well…it is not only the technology.

The real revolution is more about accessibility and, in particular, it’s about awareness.

More specifically, awareness about how we make things, how we think about making things and how we think about things that we make. No riddle intended.

A Revolution to Shape Ideas and Culture

Rapid prototyping, free form manufacturing, additive manufacturing and 3D printing. You could dispute the differences like the different flavors of ice cream. But they, more or less, melt down to reveal the same idea.

Technology aside, the significance here is the main stream “awareness” that this brings about. Again, that by itself is the revolution. How we convert an idea into tangible and functional form.

As the hype maxes out and the debris settles it starts to reveal this awareness in a deeper and more profound way. The technology starts to diverge, it diversifies. We start exploring how it might provide solution in areas from art to research and beyond. Areas we did not think of before. And, that is when really interesting things start to happen.

3D printing is now more tangible to us in our hands, minds and in society. 

It typically takes about 30 years before a really new idea can move up from concept to culture. Exponential growth. Suddenly its there. It rises very slowly and then seems to jump the curve. Jump into view. Something that moves into our minds and effects the way we do things and the ways we think about how to make things.

Moving into our culture.

As a species distinguished as tool-makers it is awareness about these things, these ideas, these technologies that fundamentally inspire and empower us.

The reason these mean so much to us is because they connects us and our worlds.

If you think about it we live and interact in 3 worlds. The interaction between the world within our minds, the virtual world within our computers and that of the real world where will all live in. Something like 3D printing enhances our ability to connect and interact between these worlds. That means a lot to us as it relates to our individualism, our independence and our freedom. Liberating our imagination.

Rapid Prototyping 

It’s not that long ago that 3D printing was considered more of a prototype method only. Something that allowed us to prototype new things very quickly. The ability to rapidly convert something from our mind into the real world. Something we can then all touch. Rapid prototyping. 

In many cases you could argue that it was only that. Convincing others that 3D printing can also be used to build real world end-products seemed near impossible. Those barriers have melted away and the situation has flipped as the idea becomes more clear, touches more people and the awareness grows. 

Such “awareness” pushes and even catapults the development focus of a new technology. That is what makes it great. What makes it powerful. We have just witnessed it before with the PC industry. 3D printing is now laying down another infrastructure. One that allows these technologies to diversify and be applied to an ever wider and deeper range of uses.

3D printing technologies are rapidly advancing and diversifying in applications. True. But like any revolution, what is real and what is rumor become intermixed as things move toward a critical mass. Belief and perception typically precede objective observation and proof. Claims overshoot reality. Things can become confusing.

That’s fine.

Its part of the process of innovation to imagine that what we don’t have or can’t be done…yet. Necessity will do the rest.

Exponential Growth

The success of one industry is typically the result of the success of another. One is built on the other. The magic happens when their streams combine. The merit of one embraces the other and that can form the seeds to exponential growth.

For Rapid Prototyping, 3D printing, it was the PC that provided the means. The success of the PC was bringing increasingly more powerful computational power to the masses at increasingly lower cost. This opened the door for this 3D printing technology to emerge. And, like the PC, it then moves it from concept to culture as it is doing so today. 30 years in the making.

Like before, that process will repeated itself. 3D printing will form the basis, the foundation for other technologies to be embraced and rise. Robotics?…Maybe. 3D printing can provide incredibly rapid solutions here to a large and emerging audience. Certainly in the realm of democratized developers.

Hammering Things Out

You can 3D print the exact shape of an aircraft but that does not mean that it is also going to fly.

Products are made using materials. Materials have certain properties which allow the product to work as it was designed to. These properties include things like strength, toughness and appearance. Its not just about the shape of a product. Its about the shape and how well the materials used in a product allow it to serve some function.

Use a hammer to drive a nail into a piece of wood. Depending on your aim you will hit the nail with hammer without bending the nail. In most cases, not a problem. A trivial, age-old process that most anyone has done before.

Now lets do the same with 3D metal printed products. But don’t be surprised if the nail and/or even the hammer dents, breaks or even shatters on impact.

3D printers can print a metal hammer and a nail. True. But creating functional products involves more than just creating the shape of an object.

There are very specific technologies involved in the manufacturing of something even as trivial as a nail. Nails are typically made of rolled, cold-drawn metal. The process involves rolling and stretching the nail metal and aligning its metal crystals in such a way that allows it to become more rigid, springy, tough or otherwise less brittle. The truth of the matter is, you never really hit the nail head on. But due to its forging it is forgiving and springs back in most cases. In the worst case it bends but won’t break, let alone shatter.

The slender high heels of women’s shoes need to be strong, allow some flex but be rigid enough for support. The heel should not break off at the slightest unevenness in the floor. The front fork of a motorcycle needs to be springy. It needs to allow slight bending when loaded yet instantly bend back as well. Like the nail it should not break. The tires of your car need to grip in a multitude of conditions, produce minimal noise and also have good wear resistance. Again, products must meet many demands in order fit some application. The materials used have been designed with certain properties using various manufacturing techniques in order to make the product work like it should. It is not just the shape of a product that matters.

Think about that for a moment the next time you hear about 3D printed firearms.

To many, 3D printing firearms is about freedom, individuality and independence. It is also about the building of perception that proves the merit of the technology. At least to some level. An incentive to prove something. But I’m not sure if a lot of engineers would want to wrap their hands around one to test fire just yet.

3D print a phone? Yes. The basic shell components only. Something to customize it to your taste. To represent your individuality. But only as a special production spin-off. Contemporary production techniques will remain pretty much the same. Unchanged. Print the chips and touch screen and a lot of its other components? Don’t think so. At least not any time soon. The CPU’s and other chips are manufactured on state of art machines which dial in to high nano-meter precision. Starting cost for such a machine…32 million Dollars.  

What these examples illustrate is that while the 3D printed shape of an object may suffice for an application there are more factors involved in making something work than would seem. This does not mean that 3D printing technology is not applicable for real world products. Actually, in the case of of metal printing technology, the development and the properties of these metals are advancing rapidly. It simply means that the technology to induce certain specific and required properties in 3D printed materials might not be there yet. Or, there may be a lot more involved to get there. These property requirements can certainly not be overlooked.

It is not just about making something work. It is also about making it work well. Certainly in every sense you would expect the non-3D printed version to work. There are also many other factors involved in manufacturing and production. What about production time, cost and output?

3D printing offers amazing manufacturing solutions. With many more advancements ahead. This is just the beginning. Again, this is just the beginning. There is still a lot to do. With that said lets move on and print a more tangible idea about the basic workings of 3D printing technologies.

The Basic Idea

The idea, the core concept behind 3D printing is actually very simple. Traditional manufacturing techniques rely on removing material until the desired shape and accuracy of some material has been attained. You know, like a chisel to sculpture wood or a lathe to cut cylindrical shapes. 3D printing or additive manufacturing takes the opposite approach. Instead of removing material it adds material. It builds it up until the desired object shape and accuracy has been attained. Bottom-Up instead of Top-Down.

Think of 3D printing as using bricks or Lego stacked and positioned to build up an object. The bricks are like building blocks connected together. It should be evident that the smaller the bricks, or building blocks, the more accurate the resulting object shape will be.

It’s that simple.

But what makes additive manufacturing so important?

There are several reasons. Probably the most significant is that additive manufacturing techniques are much less constrained in what they can make in terms of object shape. Virtually any 3D object shape can be produced within the working volume of a 3D printing system. In other words, 3D printing offers the freedom to create just about any object shape you can imagine in a single operating session. Geometrical freedom.

Cut an apple in two. The cut surfaces are cross-sections of the apple. Think of the apple as being built up of many infinitely thin cross-sections or layers. If we precisely stack up these layers we again have the object shape of the apple. The same approach applies to 3D printing. You are taking a complex 3D shape and dividing it into simple layers which are much less difficult to manufacture.

Creating layers involves slicing a 3D model or 3D scan of an object into a multitude of thin sections. Each layer is then printed out and stacked on the previous layer until the full 3D object shape is printed. The thinner the layer the more smooth and accurate the object shape will be.

The building blocks or base materials used to make a cross-section layer can be of various format. The format obviously depends on the printing technique. Formats such as sheets or beads layered onto one and other, powders connected together using adhesives or welding, or liquids (resins) which are photo-cured are employed.

The Processes

When we talk about 3D printing we are not talking about one single technology. There are several different kinds of additive manufacturing techniques in existence. Not just one. And, there is no single best solution. What is best actually depends on the application. Each technique has its own merit and limitations. Some techniques may be very accurate and allow relatively rapid print times. But they may also be very complex and costly and involve a lot of post processing. Still others may be incredibly slow (not just hours but days) yet allow prints in durable plastics and in various colors. Again, what 3D print technique is best really depends on what you need it for. What are the requirements to meet product demands.

A short run-down of the most distinctive and popular 3D print processes is listed here. What is important to keep in mind is the additive manufacturing concept involved in each of the listed techniques. The incentive here is to get a more fundamental idea about the concept using practical examples. Also, the listed processes should also be seen as a selection of the most proven and employed approaches. It is certainly not an exhaustive list. 

FDM an Entry Point for the Masses

The Fused Deposition Modeling technique (FDM) was probably the most responsible in forming the entry point for the 3D printing revolution/hype in recent years.

At least a good part of it. It’s by no means the best 3D printing technique. But it offers accessibility to a very large audience.

The working materials for the FDM process are widely available, inexpensive and the resulting prints can be durable with little to no post-processing. The concept and workings of the FDM process also require only a simple, relatively low cost design setup to get started. Together these factors imply accessibility. Accessibility for all.

The process involves the deposition of molten plastic on a flat bed using an extruder. The extruder is typically positioned using an XY linear motion system. In this manner layers are built and a 3D shape is formed.


Surprisingly, not as much focus as expected is given to this technique. This despite its merit and the fact that suppliers do exist. Laminated Object Manufacturing involves the use of sheet material such as paper, plastic, metal foils or fabrics. By using a sheet material the layer thickness is normalized, defined and is thereby easy to control. Also the process allows selective coloring when, for instance, paper is used. The printed products are very durable and resemble wood (in the case of paper).

Typically a role of sheet material is unwound flat over the working area of the printer. A laser or knife cuts the 2D layer profile as well as a grid of cuts around the object. The grid cuts are to allow the release of the model after printing. A layer of adhesive is applied after a layer is cut and the process is repeated with a new sheet layer adhered onto the previous.

The LOM apparatus can be relatively simple in construction. The materials used are usually non-toxic, low cost and easy to handle making the LOM process an attractive choice for the prosumer and small business.

The limitation is the cutting mechanism. The laser used to cut the sheets at high speeds is relatively costly and can be very dangerous (certainly for the average consumer). Using a knife instead to cut the paper may be less precise and slower. Moreover, paper is stronger and more abrasive than one may think. A knife, at the very least, would need to be made of some carbide, widea or diamond for any long term 3D printing use.


These techniques offer some truly spectacular 3D print solutions. In particular, the direct printing production of metal products. There are several variations of this technique. What they have in common is the use of powders as the base material format rather than sheets, liquids or extrusions. In addition, support structures are generally not needed as the surrounding powder provides this.

Selective Laser Sintering/Melting. Powders are fused/melted together in a powder bed to create layers, typically using a high power laser. After each layer a new layer of powder is brushed and rolled over and the process repeats. The powder is brushed away from the print after it is completed.

Other powder based approaches exist. For instance, an inkjet type dispenser dispenses an adhesive in a metal powder bed which selectively binds a metal powder together in order to build layers. This “green” product is then sintered in order for the adhesive to burn out and allow the metal powder to fuse into a solid.

Powder handling is typically a difficult and messy process. These technologies can be complex to manage and handle. Also, when working with metal powders, elevated temperatures and lasers there are many risks involved. Machine shop floor? Yes. Desktop? probably not just yet.


The Stereo Lithography process. Patented in the late 80s by Charles Hull of 3D Systems, it was not the first with the essential concept. But it formed the foundation of 3D printing as we know it today. The technique has gone through a long process of development and it has some serious merit to offer.

3D systems, the company that was built around the SLA process is not only part of the 3D printer history but is also, in their own way, setting the trend for the future. In recent times they have progressively been making efforts to consolidate the 3D market. Not just high-end but also progressively at the low-end. A kind of bottom-up approach to the marketing of their technologies. They are buying up companies in the 3D realm. Not just 3D printing but 3D scanning and everything in between. Their strategies and vision are correct but it remains to be seen if their tactics work out as they think that they will.

Traditionally, and like the SLS/SLM type approaches, the SLA technique also had some limitations as a desktop or home use device. Apart from the printing device itself, probably the most apparent is the fact that it relies on photo-cure resins to build 3D models.

The process is sound, it works. In fact, it works very well. But the resins involved are typically toxic, messy and costly with limited shelve life. All in all, too cumbersome, complex and costly for many let alone the average consumer.

But recent changes in design approaches and, in particular, the resins involved are making a difference. The development and diversity of photo cure resins and suppliers are creating a better fit for this process on our desktop.

The SLA process relies on a photo cure resin which is selectively and acutely cured to form layers. The resin in a SLA process is a liquid which typically cures under UV light. Lasers and other UV light sources may be used. After each layer is cured another layer is added in order to build up the object.

The SLA process appears to be the next candidate in the low-cost desktop 3D printing scene.

Most systems rely on the use of DLP projectors to illuminate the resin. Typically, these are fast as the entire layer is exposed in one go. This setup also requires only a simple construction to produce some amazing results. Laser scanning systems however offer other important benefits as well such very high resolution.

Explosion Of Suppliers

There are high-end 3D print suppliers on the stock market. Some of them are the long-standing ones. The ones who built the core technologies. Others are moving in with new services, solutions and technologies. Each claiming there own pieces of the pie. Nothing is static. Change is a constant.

What remains the same is how the stock market deals with the numbers. But it has most always been less of a numbers game than it is an emotional barometer. A barometer greatly influenced by belief and perception. Speculation. Those companies that may lack the core technologies but can skilfully centralize the hype and the perception can typically provide the most risky yet quickest rewards. Those that, in addition, also have the core technologies, products and solutions can offer the greatest and most long-standing rewards in the long run.

On the low-cost side, new suppliers of consumer based desktop 3D printers for home use seem to appear every other week. The majority, however, are based on the same technique (FDM). They are variations of the same thing. Different sizes and aspect ratio’s, some may be fast or accurate or have some combination of these aspects. There are exceptions such as SLA, but, typically, they are all based on the same technique, FDM.

I scream, you scream, we all scream for I scream.

One of the reasons that so many low-cost suppliers now exist is due the increasing demand for these machines. True. But in part, the demand is the result of the explosive awareness built by the democratized open development itself. The conversation just gets bigger, creating its own demand. A marketing feedback system like the ringing of a microphone that is held too close to a speaker box. Is that a bad thing? It is part of the process. But it can make things confusing.

Another important factor is that the democratized open development has made the technology (software and hardware) so incredibly accessible to all.

You don’t need great engineering skills to create a 3D printer product and become a supplier.

This is great for suppliers that lack the diverse engineering and production skill set needed to supply such technology. Skillful clients like Joe DIY who have the patience and ingenuity will make up for most shortcomings. But this also leaves a whole lot to be desired for most others. Using these products may, for many, be challenging. Sure, things will work themselves out. But for now, turn-key like a glorified coffee maker? Not really. In many cases, when you go below a certain cost threshold you get what you pay for. All in all, becoming a 3D printer supplier is like creating your own Linux distro. Hey…you don’t really need Linux skills for that.

Ultra Low-Cost

The collective. Democratized development, peer production. Futile to resist. Its workings seem decentralized and unorganized. Even a mess. This type of development seems to move in all directions like a random conversation gone wild. Development of solutions don’t always seem to follow a conventional path towards an apparent outcome. But whether trivial or vital, all and everything is taken into account.

Democratized development solutions may not always be best. But typically the outcome, the result works in all ways, not just one. Solutions best for every one.  

Still, there are shortcomings to what gets focused on. Low-cost? Understandable. It makes things accessible and allows you to take part in the larger conversation with minimal investment. It also implies to suppliers the idea that providing low-cost products will enhance their chances of building a successful business. But there is a point, a threshold, that it does not make sense. Low-cost seems to be becoming more like an obsession. Absolutism. Sure, striving towards low-cost development and design can bring forward the greatest innovation. Agreed. It can also open the door for those of developing nations to get involved in the conversation. But it can also deprive the development and design process from making good development and design decisions. Added value?

If you intend to get a 3D printer and you are serious about it, get the facts first.

Find out who is behind it all and what technologies they are using. Cost is important but not absolute. Supplying 3D printers is not just software development and a good website. It’s about software, electronics, mechanical engineering, manufacturing, production and logistics combined. Debugging is a whole new ball-game here. Does your supplier have that combination of expertise? More importantly, will they use your funding to progress development further and expand possibilities? Can they bring a diversity people and expertise together to build great products. Find that which balances cost, quality and value. Not just cost alone.

There are many suppliers doing great things. Find them, support them.  

While it may seem otherwise, only very few 3D printing technologies are available to the average consumer. Cost, complexity, safety issues and other factors form the reasons. This does not mean that they won’t one day take part as a household appliance and be as easy to use as a glorified coffee maker. We are just not there yet. 3D printing is still in its infancy. Democratized development can do a lot to get us there faster and faster. With that in mind it should be apparent that there is room for improvement. A lot of room. And, that means that there are opportunities.

As it stands, many of the low-cost 3D printers form an entry point for consumers to familiarize themselves with the technology. For many these printers find real application. They provide solution. Yet a larger segment may only seem interested in experiencing something new. They wish take part in the conversation. The printers are probably used a few times to evaluate things and then shelved. They become something like a solution looking/waiting for a problem. Part of that market goes into a hibernation period. That is until new devices emerge with a more clear problem solving application. For now, a vacuum may exist here.    

A Bit More About the Process

While 3D printing technologies may differ in their operation and control the basic processing is more or less the same. These include:

Pre-Process – Main Process – Post-Process

The Pre-Process stage relates to processing the 3D data and preparing it for the printer to be printed in the Main-Process. Depending on the technique, the Post-Process stage relates to things like cleaning, assembling or post-curing of the printed material after the Main-Process is completed.

In particular it is the Pre-Processing and Main-Processing stages were the magic happens. The Main-Processing stage pertains to the control of the machine, the printer.

If you are new to 3D printing then you may be inclined to think about the “washer and dryer” solution. The 3D scan and 3D print solution.

This is a scenario where a 3D scanner is used to scan in some, usually trivial (typically broken), part and then that part is reproduced through 3D printing. I fixed it on my own! A perfectly reasonable idea. And, this line of thought is correct. It is certainly where we are headed. But, in practice, and for most applications there is a lot more involved in the process. For home use? In many cases this approach is simply too costly, too impractical, too time-consuming. 3D scanning can be (very) complex. In many ways it is still an art. This certainly holds true when even reasonable levels of accuracy are needed. Also, preparing the data for 3D printing can be equally, if not more, complex. Sure, there are exceptions. But these are usually not the rule. For the average user it may turn out to be an impossible task to perform, especially these days. In fact, even when it comes to 3D modeled data drawn in a graphics or CAD application, things can take time to prepare and involve a lot of work. Desktop 3D printing, certainly for home use, is still an art.

The block diagram provides a birds-eye view of the typical Pre-Process elements of 3D printing data preparation. The 3D scan data process flow has also been included to illustrate what’s typically involved.


Solid Model

The 3D data used for printing must be a solid model, a closed vessel. It must be leak-proof. Think of this as modeling a house or car for 3D printing. You may have modeled the front side but what about the back side and all in between. Modeling only one “open” side would not make sense to a 3D printer. A solid model is that which fully describes the model in 3D space from all angles. Anything less than that is in the strictest sense not a 3D model, its not solid. It is certainly possible to force close a model, assuming that these closed sides are not of interest.

There are many different 3D file data formats. The standard for 3D printing is the STL file format. Binary versions are popular but text (ascii) is also available. The reasoning for ascii type format was that this allowed 3D print operators to manually examine the data if needed. The STL file format is popular but it is far from efficient. To maintain some form of readability the file construct includes an incredible amount of redundant information. In particular for 3D scan data this means that incredibly large file sizes are not uncommon. Fortunately other file format constructs are on the rise.

Object Orientation and Size

The accuracy of 3D printers is typically not the same in all 3 directions. The layer thickness (Z) may even be a constant (LOM, for instance) while the X axis and Y axis may allow for higher or lower accuracy. The minimum wall thickness of your 3D model may also be limited. All in all, the orientation in which you print your model may be directly related to the desired quality and/or feasibility of your print.

Support Material

Overhang. A 3D model may have a shape that extends over its base foot print. Depending on the 3D print technology, support material for the overhang may be required. The construct of this support material may be very important. In most cases it should not extend print time too much. It should use minimal material (cost) while allowing maximum effectiveness. It should also allow easy and quick removal with minimal surface damage to the 3D print. Most 3D printign techniques require support materials to be added. But again, not all.


Creating layers means slicing up the 3D model into 2D (2.5D) cross-sections. The minimal permitted thickness of the layers will depend on the 3D printing machine capabilities. The greater thickness of the layers the less the 3D printing model will resemble that of the original 3D data. The thinner the thickness of the layers the more time it will take to print.


CNC, NC, Numerical control. CAM. 3D printers fall back on this old but certainly not outdated machine code called G-Code. A standard in the manufacturing industry. G-Code is simply lines of “move to” type instructions with added control and auxiliary control information such as speed, tool compensation rules etc. This data is what is sent to the printer to control it in the Main Process.

The Final Layer

Its been said that science is the search for that which already exists while technology uses that to create something that has not existed before. Something new.

As a species of tool-makers, yes that is you, technology reflects our view of nature. Our interpretation of it, our philosophy, culture, society and even our individualism stem from it. There is something inherently natural about technology in that it allows us to create something new. 3D printing is our latest trophy, our latest tool to reflect and create. In many ways it mimics that what already exists in nature. And, that empowers us.

3D printing has been around for some time. Still, things are actually just getting started. The concept is sound and proven. And, as the awareness grows so also will the application and development of these technologies widen, deepen and diversify. And, this is what will make the technology great. Opportunities will always be around the corner. Its important to find entry points. Things that you can claim and offer solution in.

More of us are now more aware of what’s involved in 3D printing. What it can do, what it can’t do and how it should be done. Our collective view of 3D printing is becoming more realistic and tangible as the hype debris settles and our experience grows.

Sure, 3D printing will displace many areas of industry and change the way we make things. It will also create new areas of solution. But for now, it will compliment and co-exist with much of our existing design and manufacturing processes and technologies.

At this point we print using bits and pieces to create layers. Yet a time will come when we will start to print in particles and molecules to create structures. 

And, that will be a revolution like no other seen before.

“Is it Real or 3D Printed? What’s the difference?”

Dr. Richard Feynmann

Molecular Imprints


Foresight Institute

Dr. Eric Drexler

3D Printing and Grey Goo

Desktop 3D Printers, the Next Phase