The poured plastic should not be too soft because the surface area of the sides of the case is large with regards to the force needed to tighten and loosen. If I make the disk large enough to give support to the wrench part of the casting, this should work. We will see.
I have not made it yet, I will look at materials tomorrow (Saturday at BHV).
Yes, I know about the metal ones but I am not going to pay the big bucks for these and prefer to try to do this myself as a project.
Usil