If you haven’t seen a 3D printer yet, you’re missing something amazing. The technology has been around for a while, but recent efforts by the “maker” community have driven printer prices down.  It’s revolutionizing rapid prototyping: you can go from CAD model to holding something in your hand in a few hours.

However, there’s also a lot of hype surrounding 3D printing:  some imagine a “printer in every home” or replacing traditional manufacturing methods.

I’m skeptical.  3D printing has some very serious limitations: printers are slow, with no economies of scale. One-hundred parts takes almost exactly 100x as long and 100x the cost of one part. Even at low quantities, traditional manufacturing methods (e.g. injection molded plastic) are often more attractive.

Also, printer technologies vary widely, with a range of materials (plastic, metal, ceramic), durability, fidelity and color options. It’s not like paper printing, where anything that puts colored bits on paper gets you in the game – different 3D printing technologies have very different applications.

Hype aside, I think 3D printing will be disruptive in a few application areas:

• 100% custom “quantity one” parts (e.g. anything that touches the human body)

• Low-quantity parts. Examples: the long-tail of repair parts no longer manufactured, or “parametric parts”, where the design is a function of several parameters, and it’s not possible or practical to stock all combinations.

• Parts that can’t be manufactured any other way. What’s most interesting:  3D printers control every bit of the part volume, including the “insides”.  Most “solid” parts aren’t solid at all; they usually have a honeycomb-like interior structure to save material, but that structure could be anything.  Now, you can build parts that have interior structure that you can’t build with traditional methods.

This last category is especially exciting, and I’m hoping to see interesting designs as 3D printers get more widely deployed.