Needed to remove an octagonal nut in a tight space, for an unknown Shower Cartridge replacement. Couldnt find an octagonal box spanner anywhere so Bought a standard 32mm box spanner (sink backnut spanner) and designed this to be an interface between the two.
Perhaps it might help someone else.
I printed it upside down with supports as the octagonal end would end up too squished in the bottom layers for me, stopping the thing from grabbing the nut properly.
AMZN 3D PLA