NPR Covers 3D Printing

Last week National Public Radio had three reports on 3D printing, which is surely getting to be the flavor of the month.  (As NPR says, “the buzz is getting louder”.) I’ve been messing with low end 3D printing for almost a year now at our local Fab Lab, so I kind of qualify as an early adopter.


I’ll take a minute to sketch some background on this relatively new technology. See also on-line sources.

Everyone should keep in mind that like ordinary 2D printing, there are a lot of variations and permutations of 3D printing—so it is important to pay attention to exactly what kind of printing is talked about.  You might see some OMG fabulous thing that NASA is doing, but that doesn’t mean you can do it on your $1000 home built printer.

There are multiple techniques for the actual “print” step, but all amount to laying down slices of the object, layer by layer, just like squirting out frosting.  The layers are very thin and fancier systems have finer resolution. In the simplest machines, this is little more than a hot glue gun with motors to move it left-right, forward-back, and up-down. Other techniques use heat- or light-sensitive materials, which are hardened by precisely focused light, e.g., from a laser.

Whatever the deposition technique, the key is to convert a 3D design into machine motions.  Computer science to the rescue! Geometry to the rescue! Computational geometry to the rescue! 3D printing is the culmination of decades of algorithm development by computer scientists and engineers.

A 3D algorithm starts from a 3D design, usually a mesh which is a digital file defining the (x,y,z) positions of points, edges, and surfaces.  From this 3D geometry, the algorithm will design a set of 2D slices to build it.  Then the algorithm will create a set of “squirts” that will built each layer.

To really work, the algorithm also takes into consideration real physics, including gravity.  Many times, there are parts that are hollow, that protrude or recede, and otherwise have non-trivial geometries.  These challenges are dealt with by adding extra support which is removed from the final part.  The details differ for different machines materials, but a good algorithm can produce awesomely clever results.

This technology is very good for making one piece, especially one custom piece.  It is not really the right process if you want to make a billion widgets as cheap as possible.  But when you make your one piece, and you are happy with it, the same digital design can be sent to a factory to tool up for mass production.

Or you can share or sell the design itself.  Why go to the trouble making a billion widgets when you can just sell the design for a widget, and the customer can make his own?  Or just give it away.

Now the lowest cost printing, which is what I can afford, uses plastic such as ABS (what most Legos are made of).  It can take half a day to make a piece the size of a softball.  So, you can make a few small plastic parts, which is way cool but pretty far from a Star Trek replicator or a Lego factory.

NPR’s Discussions

As NPR reports, the same general technology can be used to “print” biologically and medically useful materials, include prosthetics such as replacement ears, organs, and bone.

One reason 3D printing is interesting for this kind of use is that, combined with scanning and skilled measurements, the “parts” can be customized to each person, which is essential.  Since you only need one or a few pieces rather than millions, it’s fine for it to be slow.

This technology is under development in a lot of labs, and should be available soon. I would expect there to be expensive commercial products and some freely available open source versions.

In a second story, NPR covers another aspect.  They report on what is now the standard trick pony for 3D printing:  scanning yourself with a kinnect, and then printing your own plastic action figure. We do this all the time in our Fab Lab, though I am a minority of one who thinks this is the stupidest possible use of scanning/printing, ever.

The same report goes on to the inevitable implication of this: you can scan an object, fiddle with the digital version, and then make as many copies as you want.  Ask a lawyer what the word “copy” means:  it means “copyright”.

There are certain to be vast amounts of controversy over the use of 3D printing, just as there have been over music and video recording.

Actually, this is a vast and really interesting topic, since the copyright or patent can (and usually should) apply to the digital design.  The legal structures around rights, derivative works, and so on are way, way out of synch with these technologies, so there will be serious legal thrashing here. You might want to check out some recent books that have a lot to say on these topics.

Lessig, L. (2008). Remix: Making Art and Commerce Thrive in the Hybrid Economy. New York: The Penguin Press.

Plotkin, R. (2009). The Genie in the Machine. Stanford: Stanford University Press.

Stay tuned, this story ain’t over.

I note that last month NPR was wringing its hands over 3D printers making parts for guns.  I note that all MIT affiliated Fab Labs and many community maker spaces discourage making anything dangerous.  But obviously, anyone can get this technology and do it.  So the question isn’t “oh, dear, how can we stop it”, it is, “how do we keep things civilized”.  I would note that a) plastic guns are not especially useful (and you’re a fool if you trust one) and b) 3D printing is a long way from producing ammunition or other explosives.

Finally, NPR did a call-in with a bunch of topics.  One of the important things from this piece is that young people have access and are using this technology.  Yes!  Tools in the hands of the workers!  The cat is out of the bag.

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