https://www.amazon.com/FINDMAG-Refrigerator-Whiteboard-Multi-Use-Magnetic/dp/B08M45FTQ9/ref=psdc_1265130011_t1_B096FF7142?th=1
3d Modeled to use these or this size magnets
Light sanding of the magnet hole may be require
For the GCODE I did rectilinear infill and I did two color changes through the Prusa Slicer
The author hasn't provided the model origin yet.