double row penholder

When making the single ring variant for >20 pens, it becomes huge. Adding another row helps keep it small.

It can probably be modified to add more rows...

The two photos are of the first prints (white on a BCN3D Sigma at high quality) the "silver" on a Prusa i3 MK2.
9.5 mm pen diameter is probably on the small side, but at least it came out the way I specified it in the scad file.

BTW, I use openscad on linux, generate an STL file, which my colleague slices in Cura on windows for the specific printer.