Either stick to a surface using double sided tape, or twelve (quantity of 12) 12mm x 3mm neodymium magnets.
Printed out of TPU 98a for added durability. Use flush cutters to remove tree supports from the two retention tabs that hold the roll on the holder.
Model is editable in onshape.com
The author remixed this model.
Based on a model identified by onshape.com as owned by Mike Winfield who may or may not be the original author.
I modified the base to create a larger contact area for holding magnets or tape & added the marker / pen holder.