This is a holder for 21 PC-1M Posca Markers. It holds them cap down to keep them from drying out and I liked it better that way.
I've included versions with and without hooks for use on the IKEA Skadis pegboard.
The walls are pretty thin, only 1.5mm in most places, but I was able to print it at draft resolution without issues as it's a pretty simple model. Let me know if you have issues with the wall thickness and I can make a version with thicker walls. I'm new to 3D printing.
Ikea Skadis hook by syfq91 on Thingiverse: https://www.thingiverse.com/thing:4964991