It's possible to print in dual color with a normal printer.

At the start of 9th layer insert the GCode command for pause the print, the command depends on the firmware

Klipper = PAUSE

Prusa/RepRap = M601

During the pause you can inser the new filament and resume the print.

There are 2 files, one with the guide to glue 8mm circular magnet, and one for the 6mm circular magnet.