Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4927432.

Based on https://www.thingiverse.com/thing:3585059 and remixed in Tinkercad (https://www.tinkercad.com/things/lfhW2cqGIi8). Scaled original to 87.7% on the X and Y axis to make the internal opening just slightly larger than 91mm, giving it a nice snug fit on the Fluidmaster flapper valve assembly nut. Printed mine out of PETG which held up like a champ. This sucker was hard to get off!

Needed this to get the nut off to replace the rubber foam gasket seal which had started leaking. I plan to model a mold for a replacement gasket made of two-part silicone which should last for ages. Link for that coming soon.