This is a gear profile with a large base and top, yet lofted inward towards the center.  I added a sphere in the center, which touches the build surface but is not attached to the rest of the object. Use your own judgement when printing, of course... but I would like to think that a good printer could create this object without using support (therefore I've added none).  The bottom of the sphere would be my only concern, not using support. This is a new design, and I have not tested it yet.  The idea is that the ball will roll around inside the gear-shaped 'cage' when you move it around.  Therefore, the ball needs to have some weight to it.  (I'm suggesting at least 15% infill for this print.)  I left the top open, so you can see down inside.  I think this would make a really nice 2-color print, but I don't have that capability with my 1.0 Pro.  :/  This was designed in inches, not millimeters.  Adjust accordingly.  I have several other variations of this design almost ready to post, so hopefully someone likes one of them.  :)