Maybe I'm way too excited about this, but I thought this was pretty neat.

This guy printed his own engine and transmission.

[ame="https://www.youtube.com/watch?v=mmK_LWOqRp8"]3D printed Toyota 22RE engine - YouTube[/ame]

[ame="https://www.youtube.com/watch?v=SB34I33Bqrg&t=34"]3D printed transmission - YouTube[/ame]

I'm no Toyota mechanic, but it looks fairly accurate and the tolerances look great too. It doesn't look as good as a metal model, but heck, it works.