Well, here is is, my first ever CAD file for sale.  I am open to feedback etc.  Please let me know if there are any issues you find.  I am selling as a 3MF file so that it can be easily printed in multiple  colors versus an STL that you have to "paint" colors on.  Also, holes are set to 3.13mm, based on my testing using a .2mm nozzle when printing this yields a tight fit for a 3mm x 1mm disc magnet, your milage may vary depending on  printer.