Casting Can Vaseline Prevent Resin From Bonding to Itself?

I think that could work... it would certainly help, but you'd need to be fairly generous with the vaseline. Would you be able to just make the one mold and test it, and then if it doesn't work after a few tries, make the second mold, or come up with a plan B.

 

You have to be REALLY scrupulous with setting up to pour the mould - I used a two part mould for my mermaid tails using rigid Polyurethane and despite spending hours making sure there were no undercuts it still destroyed my master when it got under a scale - I used Vaseline very generously on a soft brush to keep the two mould halves apart and was able to lever them apart with a small blade without any difficulty after cutting away where the resin had seeped down the side of the mould box onto un-vaselined areas.