Sphericon
Files include 3D printable model as well as 2D versions which can be laser cut out of paper and folded into a sphericon.
More info on the sphericon: https://en.wikipedia.org/wiki/Sphericon
Files include 3D printable model as well as 2D versions which can be laser cut out of paper and folded into a sphericon.
More info on the sphericon: https://en.wikipedia.org/wiki/Sphericon