I had some 6x3 and 7x3 neodymium magnets laying around so I made a remix of a magnetic pin made by Steinbauer3D becuase I like the design. 

The pin uses 3 x 6x3 magnets (one maganet will be very weak) that are glued and press fitted (I use a vise to fit them, glue is additional for extra strength) and on the bottom I added some tape on the bottom so the surface will not be scrtched.

scaling the model by the hole at the bottom (using measuring tool in slicer) will fit the 7x3 magnets.

Printed at 20% infill and 0.2 layer or 25% and 0.15 with PLA (strong enough to press in vise)