Inspired by MakersMuse and MakeAnything.
Thanks guys, these things are so much fun!

• print two of the Sphericon1.STL and one Sphericon1_insert.stl
• Scale as you like. but bigger defenitely rolls a lot better than smaller.
• insert is made for a model with 0.25mm gap. rescale as needed for your printer.
• Small layer height makes it roll better, so 0.15mm or smaller.