Summary

Pieces to do a levitating ball magic trick.

Assemble, add 3V motor with two AA batteries and switch, make the ball levitate.

Instructions

The idea comes from my daughter to construct a magic trick: the levitating ball trick.

If somebody knows a good way to make a foam light weight ball, let it be known in the comments!

The idea is simple and based on a game she has: a fan blows wind, this levitates a ball into the air where it hangs.

1/print the three pieces
2/place motor in the engine holder
3/drill hole in the fan sufficiently large to fit on the motor, glue it in place so it rotates freely away from the plate. Note that the flat piece of the fan is TOWARDS the motor.
4/fix the motor with tackt or glue or ... so it does not move anymore
5/close the device by adding the top plate. Verify that the fan rotates freely, then glue together.
5/connect motor to batttery and switch. Careful, only one rotation works and the rotation is counterintuitive for most people! The fan needs to rotate clockwise when looking at the hole in the topplate (and flat piece of fan is at the back then. The fan pushes the air radially out and towards the guide hole.
6/test with very light balls. Foam balls will do the trick. Some numbers:

3 V small motor
0.3 A needed for a foam ball
0.9 A needed for small printed ball, eg from http://www.thingiverse.com/thing:67452 the extrathinshell stl. In last picture you see this ball does not go so high. More Amp would be needed to make it go higher.
Use a trim pot to make the ball go up and down

Ancestry: I reused some of http://www.thingiverse.com/thing:13829 functions to create the spiral. The battery holder you see in the images is http://www.thingiverse.com/thing:5079 while the blue ball in last pictures is thing http://www.thingiverse.com/thing:67452. A foam ball works better though, eg isolation expansion mousse you cut in a ball. The ball must however be perfectly round, or it will be pushed away, instead of floating in the air.

Levitating ball act