A few years ago I made a picture of the 3-adic numbers in answer to a MathOverflow question (using the free 3d modeling and rendering software Blender, which I highly recommend despite its steep learning curve). Recently I discovered that I lost the original file, so I recreated it, with the following result:
After I posted the picture above on Twitter, Matt Kukla, a budding mathematician and student at the University of Maryland, asked for the source file, and today, he’s posted a beautiful 3D print of the 3-adic numbers!
EDIT 5/19/2019: If you’d like to try this yourself, here is the original .blend file and here is an exported .obj file.