I saw a similar holder for glove boxes at a local store and thought it would be easy enough to model and print my own way. This allows for mounting using screws in the keystone slots, or using (6) magnets.  If it slides with the magnets, just put a little gaffers tape over them for traction.

Tested with Costco, Harbor Freight, Home Depot and a few other misc. glove boxes available in the US. Appears to be a standardized size, except length. UK/EU/AU/Etc. may be different…

Update: Added a smaller/shorter variation that will print on the Prusa Mini and only uses (4) magnets. (Thanks Bugman_140 for the suggestion!)