Warning! Be careful not to let small children reach the magnet and swallow it!
All you need is a small magnet, 10mm in diameter and 3mm thick. I used a neodyne magnet with 0.8 kg power. No glue needed.
I changed filament (paused printer) from black to white after the last black layer in order to get white characters. If you cannot do that you can always paint in white or a light colour. The base measure is 40mm x 30mm x 9mm
Place the magnet inside the pocket of the knob and place the knob in the hole so that it points to Clean or Dirty. Place the complete dish indicator on the dishwashers door and set to Clean when you start the dishwashing . When the dish is removed from the machine, turn the knob to Dirty.