Good news for anyone who dropped a small fortune on a 3D printer and found themselves bored of creating novelty keychains and meme-based figurines. Jose Julio successfully turned the parts needed to build a RepRap 3D printer into an air hockey-playing robot that looks pretty tough to beat.
If your roommates or family straight-up suck at air hockey and you want a real challenge, Jose has posted detailed build instructions here, as well as 3D models and requisite software here. The usual caveats apply in terms of having some pre-existing level of skill to build your own—this isn't like putting together a Lego kit—but the good news is that you can probably turn it back into a 3D printer to fix or replace whatever it is you smash after continuously losing. [Ciencia y cacharreo via IEEE Spectrum via Hack A Day]