I made a test magnetic movement tray for 1/72 miniatures. Used magnetic sheet glued in cardboard and an Spray Stone effect from Rust Oleum. I can try to drybrush and decorate. :
Magnet Circles for Wargaming Miniatures from £6.95
Magnetic Sheet Combo - Self Adhesive Wayland Games
▷ Magnetic Sheet COMBO - Self Adhesive | - GSW
Magnetically Receptive Base Sheet for 4L, 9L and 9L XL Boxes from £10.95