A marble machine with climbing marbles and changeable tracks.
No hardware other than the ball is needed unless you install the optional motor.
Currently only two tracks but more to follow.
Youtube: https://www.youtube.com/watch?v=ca_6G2sM-TY
Youtube: https://www.youtube.com/watch?v=-xvpLN2a9e8
Printed everything on a printrbot plus 0.3mm layer height 20% infill.
Prints without supports.
Balls are 9,5mm steel balls: http://www.ebay.com/itm/BALL-BEARINGS-9-5MM-3-8-PACK-X-100-/200970728122?pt=LH_DefaultDomain_0&hash=item2ecac9f2ba
Optional:
There is a motor mount and gears if you want to add a motor
There is a hole in the motor box for a DC connector.
Micro Gearmotor 75:1 3V: https://www.pololu.com/product/2366
DC connector: http://comingsoon.radioshack.com/size-n-coaxial-dc-power-jack-w-switch/2741583.html#.VWjWWs_tlBc
Let me know if you want a battery box instead of the DC connector.