Well you could corner the market on tennis shoes for dust mites.... but seriously, if you could use a conductive medium in the printer you might be able to build some efficient heat-to-electric thermionic chips...

http://www.powerchips.gi/technology/Powerchipstech3Jan06.pdf

My compliments on your creativity!

The applications wouldn't be so much for printing small things but for resolving fine detail and dimensional tolerance.

It's pretty amazing and I'm tempted to invest and play with 3D printing right now but at the rate that the technology is being improved/refined/ reduced in cost I'll wait, probably not too long, until really good out of the box 3D printers are cheaper and better than now. Remember the first digital cameras?

Michael Crichton (author of Jurassic Park) got there first, in his book Micro. The way he arrived at the miniatures was different, but it makes a great read.

Definately not too small, they show a model of Tower Bridge at 90µm between the towers. We already use structures 1µm wide in our products. If only they could print metal parts........

What kind of products?

Image intensifers.