Magnet cover is designed to separate so all the magnetic stuff you've picked up just falls off.
Takes 4 qty of 18mm dia x 3mm magnets.
Holes are slightly oversized in the base for magnet install.
Super glue the magnets into the base.
Total assembled piece is 50mm x 50mm x 28mm tall. (2"x2"x 1 1/8")
Magnets I've designed for, for reference. Not an affiliate link.
https://www.princessauto.com/en/3-pc-magnetic-discs/product/PA0008713422
(Never buy these a full price)
The author marked this model as their own original creation.