Summary

This is the base of a hanging artwork.

Do You have two or more things to balance and spin?
Then you could use this OpenScad-file to make a mobile.

Example:
Mobile for saving coins.

Instructions

Use a bottom-up strategy. Start measuring the lowest group of 2 items. Enter their weight m1 and m2 into the scad-file. Check the object's sizes to prevent collision of parts. Then set a length of the base in the scad-file. Print it. Check the balance. Then continue to the upper level.

I used an average density of PLA ro=1.320/1000 (gramm/mm^3).
For ABS you can set ro = 1.08 /1000 for light objects (not tested).

The Coin Mobile Example:

In addition to all printed part you will need the coins and some string.
Print 2x 1EUR frame and 1 x 2EUR frame from
http://www.thingiverse.com/thing:22901
Insert the coins. Connect the 2x 1EUR frame to the mobile_p1.stl base.
Then connect it to the mobile_p2.stl base. Then connect the 2EUR frame. Done.

When finished the assembly I realized coins are obviously not a good choice for fast spinning. The surface/mass ratio is too small. You might place it near a door or a window to get enough air flow. Maybe hot glue some paper wings to each frame! ;-)

Any other ideas what to do with foreign currency coins after vacations?
Please show me your ideas of spinning 3D-objects.

Parametric Mobile, Sculpture Base