My new mold plan... Comments needed

[Merman Lir]

So I have a photoshoot (hopefully) next weekend... I'd like to make a silicone accessory before then (a 2.0 version of my headpiece fin) so I'm working on a deadline and trying to use stuff I already have. I have dragonskin and pigments.

I also have a half sheet of dense 2" thick foam (used for construction insulation). my thought is to carve the negative into the foam and then coat it with resin (or some other silicone friendly sealant) and use that for my mold. I'm wondering if that would work. otherwise, I have to find enough clay to make a clay mold.

think that would work?

[Merman Lir]

if you were wondering. this didn't work. It probably would have, but I found it too difficult to carve the foam cleanly.

[Merman Storm]

If its the yellow polyurethane foam, you sand it to shape it. Dremel type tools work.
You could also get close with the foam, then coat it with clay to carve the final details.