This is a little car for BRIO Style Tracks! Should work on other tracks as well... I have included the design files so you can adapt - change it to your needs! Did not design the couplers yet - I leave it up to you to come with some creative ideas...
;) Next version will have magnetic couplers - just need some time!

12.06.: Update: Added Hook & Ring Coupler, drill a 5mm hole in the body and use some glue!