These are the Monarch alliance rings from the TV series Miraculouse. They have an inner diameter of 15.8 mm and therefore fit the fingers of 4 - 6 year olds.

I have already coloured each ring so it just needs to be configured with the right filament.

I have also created a print-in-place folding box to go with the rings, which has space for 10 rings. You can download it here: https://makerworld.com/en/models/380031#profileId-280197