So, Amazon has opened a 3D Printing Store. The selection's pretty limited, though, and you can't print arbitrary designs. It's hard to get excited about this in a world that already has shapeways, sculpteo, pinshape, etc.
I've honestly found it difficult to get excited about consumer 3D printing in general, because what I consider to be the obvious use case - printing your game characters - is incredibly underserved. You can print your World of Warcraft characters, you can print your Minecraft worlds, and that's about it. (You used to be able to print your Rock Band 2 characters, but that stopped when Rock Band 3 came out.) I would pay a lot of money for a print of my City of Heroes main, or my character from the Saints Row games. This would be great even for games where you just customize an existing character - I can get a Team Fortress 2 Medic, but I can't get him wearing the right hat.
I hope we get to that world someday. I do enjoy iconic, established characters from beloved games, but I have much more personal attachment to the characters I've actually created - they've been imbued with a piece of myself. Nobody else has one quite like them.
Relatedly, with Nintendo coming out with game-enabled figurines of their cross-game characters called "amiibos", it's a perfect time to ask again - why can't I get a print of my Mii? More than one of the amiibo-using games allows you to play as a Mii, so why not sell amiibos of actual Miis? I know it can't possibly look as nice as the other amiibos, but it would be yours in a way the others can't be. I know I'd get one.