Art Pen Holder

My daughter's really into art -- so much so that (without a bit of help) her desk could easily turn into a pile of art pens. So she was looking for a way to organize all her markers, and I cooked up this design in order to help.

My family artist prefers Prismacolor and Copic markers, so this little gizmo is sized to comfortably hold 36 of either -- obviously, it'd hold smaller pens and pencils as well. Print one top, one bottom, and four corners -- add a bit of super glue, and you've got an organizer!

26 Dec. 2017 Update:
Since Simplify 3D now behaves properly with thin walls, I revisited this design and uploaded 3 revised files (with "_thin" suffix) -- these have thin (0.8mm) walls between the cells, allowing for slightly larger cells for those... difficult... pens.