I've tried the urethane rubber for the mould with the last attempt. I had a few bubbles & the detail was poor compared to the silicone. I also tried a clear plat silicone & it wouldn't set.
When I first started experimenting with the tendons I cast some parts with a shore A20 urethane rubber & its plenty stretchy enough for the job. I cant get clear in anything softer than A55 though An A55 hardness will work really well for the lips as they don't need to stretch its also UV stable & crystal clear. The tendons that need to stretch are the small piece in the corners of the mouth, the thin one that joins it & the biggest tendon that connects top & bottom, all of which I reckon I could get away with casting in the shore A20 with a white tint & then a they can be blended with a little airbrushing.
What do you reckon?
I have thought about making two different jaw castings but I really want this to work, so we'll see how this goes & I may end up resorting to that option.
Thanks for the thoughts