I modeled these magnets for an upcoming cruise to give away to people in other cabins. I modeled these in Fusion 360 after an image file I found on the internet. The .STL has both shapes, but the .3mf file allows you to move Mickey and Minnie around the print bed independently. The Fusion 360 source file is also included.

The recesses in the back are sized for circular magnets that are 8mm diameter and 3mm thick. They will probably be a tight press fit, but you may also want to glue the magnets in the back with E6000 glue.

This file is intended to be printed in two colors, with Minnie's bow a different color than the base. Unlike my pumpkin magnet which I uploaded as two files, I learned a simpler way to print in two colors for simple flat areas: https://support.ultimaker.com/s/article/1667417981430. Use a support mask that is 6mm or 6.1 mm high to make Minnie's bow print with a different extruder. Or just print her all as one color and use paint/marker on the bow afterwards.

One more note- there are multiple people that will sell you this image for a couple bucks on Etsy, but I can't tell who the original artist is. If the art is yours (and you can reasonably prove that it is yours) I will take this file down upon request.