Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4459878.
This uses a ceramic magnet diameter 18mm and height 3mm. Printed in 3D Warhorse blue PLA and a Silk Black PLA of another brand. Used the color change feature of PrusaSlicer to have the print pause at the right layer so I could manually switch the filaments. I printed two: One in blue with a silk black (silver) layer, and one in silk black with a blue layer. The filament should be swapped just before the layer that bridges the gap over the hole for the magnet (3mm) and again just before the layer where the symbol starts (3.6mm). During the first color change, I inserted the magnet into the hole. This is not necessary, because the pert is open on the bottom to insert the magnet, this just insures that the magnet will sit flush inside of the part.