I have a dozen or so 20mm calibration cubes lying around , and I sit there and will pick one up while waiting for a print to finish , and I will start to spin it on its points. So I decided to just throw this thing together as a goof to put one of these cubes in and be able to spin it without losing a grip on it. Just for fun and entertainment , nothing else. Takes a little force to get the cube in there , but fits pretty nice and spins with little effort.

I was using these calibration cubes to calibrate my printer . https://www.thingiverse.com/thing:1278865