The amount of each piece needed to print is included in the part name, and assembly should be pretty self-explanatory. Please leave any feedback, good or bad!

This was printed by a150587 with the fixed pin design and it is confirmed to be working!

UPDATE
12/27/13 Made it simpler by implementing a "snap" pin, now two more regular washers are required but the number of unique pieces was reduced from 6 to 4.

1/2/14 Happy New Year! Included fixed pin design courtesy of a150587. Thanks! NOTE. The source file for the pin is for the old pin design, which does not work as is.

1/15/14 Modified wheel design, it should print much nicer now.

Instructions

In order to build this, print the designated amount of each piece. Base piece must be rotated to upright position first. The amount required of each piece is stated in the stl file. ABS recommended, but PLA should work just as well. Sparse inflill (10-20%) should work without a problem, print with more shells for better durability.

Assembly

1. Place the base piece on a surface, flat side down.
2. Push the pin through one of the holes, the flat head should be on the outside of the base unit, not in-between the two arms with holes.
3. Place a washer on the pin.
4. Place a wheel on the pin.
5. Place another washer on the pin.
6. Push the pin through the other hole of the base piece.
7. Add one last washer to the pin. Apply glue or use a wire if needed to secure the pin in place (should not be required with a well calibrated printer)
8. Repeat steps 2-7 for the other hole of the base unit.
9. Repeat steps 1-8 for the other base unit.
10. Profit.