I'm making a wet layup mold so I can replicate my car's doorsills in carbon fiber. door sills in question are plastic BMW E30 sedan ones.

I wanted to check with someone who knows what they're doing whether my mold will work well or not.

 I plan on gluing sheet styrene on top of my birch baseboard, and then on top of the styrene I plan on hot gluing my trim from the bottom. I know I'm going to need to make some fillets around all the sharp edges to avoid mechanical adhesion but can I use MMD green hobby putty instead of plasticine/oil based clay/yellow filleting wax (like I see a lot of people using on the forums)

also, I'm not sure how I plan on making a flange on the triangular piece of the trim. I drew a crude side view in MS paint to help illustrate my ideas but if anyone has a better idea I'd love to hear it.

I wanted to ask, do I need specific pigmented tooling gel coat or can I just mix up some polyester resin and let it get tacky and start laying on my fiberglass matt? I watched the video by carbon mods and he uses a thick lime green gel coat to make a mold of his replica part and I also see a lot of people using this same technique.

thanks a bunch