Meissner Tetrahedron

thingiverse

This is the design of an object of constant width, also known as Meißner Tetrahedron, which itself is a slghtly modified Reuleaux tetrahedron. Print three of these tetrahedron and place something flat (like a book) on top of all three and it will roll, just like on spheres. No promises, but I think you will be amazed! The stl file has a high resolution, and is intended for scaling.