The initial casting with the MD-50 elastomer produced a pretty nice looking product. It was really bendy when it came out of the mold, but after 16 hours at 70C it stiffened up considerably. The walls are definitely too thin and the DIN clamp needs to be beefed up.
It would be nice not to iterate blindly, so I hung a water bottle on a paper clip and filled it with a couple different weights of water. With 100g of weight I'm seeing about 8mm of displacement.
With some hackery I created a material in Fusion360 that produced similar results. Note: These are not real values! Don't expect them to do anything remotely correct.
So hooray for that. Time to tweak some parameters and build some bracing.
In other news: I'm having some luck casting directly into PLA without bothering with making a silicone mold. I need to do some more experiments.
Also, my fail of the week was trying a significantly more rigid resin in the mold. The walls are far too thin for this stuff and it didn't survive demolding.
In any case, it was a good reminder that things that are rigid are also usually brittle.