Who doesn't need a ruler? The most practical and useful print out there that only consumes about 10g of filament. Perfect print to use your filament left overs on.
For multicolor print either use AMS or simply download raw model file and pause at layer #9 to change out the filament.
You can download 100mm ruler from here: https://makerworld.com/en/models/440402#profileId-346072
You can download triangle ruler from here: https://makerworld.com/en/models/388125#profileId-288847