Marble Arc
thingiverse
People will definitely appreciate a tiny decorative piece that can host a marble show. It's up to you whether to put several marbles on it and watch them move, or just place one and let it roll freely.
Download Model from thingiverse
With this file you will be able to print Marble Arc with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Marble Arc.