i used 2 magnets and printed the 15mm pin and the wheel
At the 15mm pin, glued on a 10x10x5mm magnet.
And the other magnet is round 8x3mm, to go on the hole in the extruder.
Printed this in PLA with green to yellow color change filament.
0,2mm layer hight
Please press Like, before you print this..
And please send me some money, if you have plenty (i have not)
happy printing and good luck..!