So for the new mold, I decided to try something different:
Using a photo of a claw on this cutting mat, I was able to model a case to scale in blender for the new molding, with keys built in around the claw to help the silicone consistently stay in the right shape each pour.
I 3D printed it, flipped it, and printed it again to make both sides.
I bolted it together to make it water tight, poured the silicone, and ta-da! Custom fit mold box. I originally used bolts to hold it together, then clamps, but binder clips were quicker and worked way better.
I also sculpted a stand out of moon-sand and eyeballed it to be the shape of Isla Nublar when viewed from the top— but moon-sand was a BIG MISTAKE. I definitely don't recommend using this as a sculpting medium for mold making. I only did it because I had some on hand and though it would work well for that rocky texture. It worked out in the end, but t he silicone seeped into the sand and didn't cure for a while. It was a real mess to clean up.
Panting this from the raw color of the concrete was a pain until I remembered I had charcoal concrete pigment.
And speaking of concrete, I've also been trying to get a concrete claw because the weight and feel of it is just that much better— feels like a fossil! Too bad it's as delicate as one too... the tip keeps breaking off. I'll figure that out eventually.