Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4545834.

Just a simple boardmarker holder for the office. These markers have a larger diameter (of around 20mm) than most other markers I found on Thingiverse.
Just import into Cura and slice.

Add two or four strong magnets (10x2mm) with superglue to stick penholder to the whiteboard. :-)

(Please ignore Manifold errormessage in Cura.. it will print fine!)