I created a model to hold the up to 6 pens/marker that came with an Acrylic Calendar. The Holder can have 10x3mm magnets glued to the back of it.
Printed on a MK3s+ using Inland Blue PLA Filament @ 15% infill.
Calendar: DIYMAG 3Pack Acrylic Magnetic Dry... https://www.amazon.com/dp/B0CDPSQRQL?ref=ppx_pop_mob_ap_share
Magnets used: TRYMAG Small Refrigerator... https://www.amazon.com/dp/B09SLDQYVY?ref=ppx_pop_mob_ap_share
The author marked this model as their own original creation.