Made this because I keep changing between the 0.4mm nozzle and the 0.8mm nozzle and forgetting which one is currently in the hot end.

The arrow might be a bit obsolete because you can just look at which one is missing but might be useful if you have taken out multiple. Either way, it's printed in 2 parts that slot together and then slide into the track on the main body.

Next plan is to make a cut-out on the bottom and have it fit onto the top bar of my ender 3 Pro, or maybe have half the body on a hinge which folds back to reveal storage space for even more nozzles!

I printed in white and swapped to black for the last few layers to really define the numbers but you can print in whatever colour your heart desires :)