PolyGauge with Magnets

Excited by Bwolfey's design https://www.thingiverse.com/thing:3242275 for the poly gauge, I've done minor modifications: instead of fit press mounting of the knob, I've embedded some magnets into the print. This allows the knob to snap into the right position.
Added four magnets in total (different sizes) can help, but two 10mm x 4mm are sufficient. However take care to place them in opposite polarity, one with North up and the other South up - so you can place the knob from both sides.

In order to place the magnets, I've used PrusaSlice 2.1, which directly allow to add a filament change right before the cover of the magnet positions would be placed. No need to change the filament, however, this will pause the printing process and the magnets can be placed easily.