Here is a set of clips used to mark copper and PEX plumbing. The clips snap onto 1/2" or 3/4" pipes and allow you to add label maker text...or you can just use a Sharpie marker. STL files are included for both vertical running pipes and horizontal running pipes in each size.

I used PLA with 20% fill at 0.20mm resolution.

There may be cases where printing with a filament that changes color with temperature might be useful. (I haven't tried this.)

Creality

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