Autobot Keychain Pendant.
My son had a Autobot birthday party and I made these as party favors. The kids loved them.
I remixed the autobot pendant by making the autobot symbol thinner and 1.5x bigger: http://www.thingiverse.com/thing:376605
I used 2 filaments colors to get the multicolor effect. Once the print job starts on the autobot symbol, immediately pause the print job and change out your filament color.
I used .2mm layer height and 20% infill.