I wanted one too I 3d printed everything on my Flashforge Dreamer and ordered some electronics from hobbyking. To fit the electronics I made some custom parts. Wrote everything up on Thingiverse: http://www.thingiverse.com/make:275281
It even drives: https://www.instagram.com/p/BN4VzIkA2gE/?taken-by=n0n3u5 !
Now Iโm searching for a better track than my apartment