Hyperboloid Pen Holder (2016)

https://www.thingiverse.com/thing:1401060

A parametric 3D print design can be configured to hold any number of pencils. CC BY 4.0 license. You can sell printed objects but please give credit!

Hyperboloids are mathematical objects classified as ruled surfaces. This means that for each point on the surface, there’s a straight line (or in this case, a pencil) that goes through that point.