This is a derivative of Jaylan's C&LFS, in that I looked at it long and hard before designing my own from scratch. ;-) It's cheaper because it requires no nuts, bolts or other non-printable parts other than marbles. It's lazier because only the two files with the word "spindle" in the name were actually designed for this thing. The other parts came from other designs I'm working on and they fit a little loose because I was too lazy to adjust them for this design. I substituted a little krazy glue for the missing elbow grease and it seems to work fine.

Print out 10 spindle wedges (a_spindle-2.stl), 8 curved arms (a_spindle-3.stl), one square axel, two couplings and one 9v holder. Snap 5 wedges together to form bottom ring. Place on flat surface so the marble track faces up. Insert axel into one of the slots on the side. Attach coupling to other end of axel. Attach curved arm to coupling so that it curves up. Add another coupling and curved arm to first curved arm. Push 9v holder onto end. Add slightly fewer marbles than it would take to completely fill the track. Snap remaining 5 wedges together to form top track. Attach remaining arms to side slots so that the track faces down and place on top of marbles. You may need to place something heavy in front of the filament guide to keep the spindle from sliding.

TIP: If you are looking for marbles at your local HugeMart, don't bother with the toy section (marbles are choking hazards, dontchaknow)-- head over to arts & crafts. I was amazed that even the standby Kerplunkâ„¢ had the marbles replaced with little plastic aliens licensed from Disney/Pixar.