This is a simple inverse magnetic "pendulum", it uses powerful embedded magnet to create the effect of a levitating object. Use a thin nylon chord, fishing line, etc to attach the weight metal part and insert it in the lower hole, fix it it with a M3 screw o something. The powerful 30x10 NIB magnet inside the upper part will create a magnetic field strong enough to keep floating in the air small ferromagnetic metal objects, just fix the fishing line at an apropiate distance. The effect of a pendulum that keep its position even inverted is awesome!!

At print time: You will need a software/printer that can pause print at a custom height to be able to insert the magnet in the pendulum at mid print, and also to insert a 12mm steel ball in the weight cube. Dont use support for print. Remember you can even use a ball from some old Newton craddle you have around, these steel balls already have a hole for the fishing line. You can also use any other metal piece to make it levitate. Pics shows a part using a 20mm stainless steel ball harvested from an oldie Newton's cradle. If you don't have a 30x10mm magnet you can use any other size and adapt it to the room using plasticine or an adapter or something, or just edit the included CAD sources, it is a very simple design.

Keep your visitors amazed !! Enjoy!

UPDATE (30-MAR-2017): Added a model for a 10x10x5 mm magnet weight. You'll have to pause print to insert the magnet, In case you have a ferromagnetic nozzle stick it with a drop of glue and continue printing. This magnet loaded weight allows for an increased distance from the main magnet making the levitating effect even more awesome.