I'm trying to make molds from acrylic plastic parts. I know that the styrene in the gelcoat is not compatible with this type of material. I've tried several different methods of sealing the parts before attempting to make the molds. So far I've tried 2 part paint in my shop with 5 coats of paint and 5 coats of clear, this was a urethane paint. I also tried epoxy paint and epoxy resin. No matter what I try the part and the mold are both ruined. It melts the plastic very badly even under the sealing coat, but the sealing coat remains intact just very distorted. I've been extremely careful making sure that coverage is complete when trying to seal the parts. I've ordered a new interior for my car which is a 2017 corvette so I can try again, just not very cheap. Can someone please give me pointers on how to make a mold from these parts? At this point I'm thinking that the unimold system just is not going to work for these parts. I don't want an overlay I'm trying to make the interior out of 100% carbon, so I really need to figure the molds out. 

Thank you!

Thanks, I'm relatively now to this. I've only made molds using gelcoat and fiberglass in the past. I'll try and research about epoxy molds.

I never heard of a polyester based tooling gel coat. If there is such a thing, it would be very counter effective to use it in this case.

But yes, the procedure is basically the same.
Gelcoat, then glass fibres with epoxy resin.
But usually you should use woven glass reinforcement, because shopped glass mat doesn't get soft, when used with epoxy resin.
Additionally you have to continue after the gelcoat in a fairly small time frame. Unlike polyester gelcoat, epoxy gelcoat doesn't cure to a tacky stage. There is only a window of a few minutes, where the epoxy gelcoat is "half cured". This is the point the reinforcement should be applied.

A good alternative for small parts is epoxy tooling putty.

Alright, I've been using the unimold system from EC. So basically I just need epoxy gelcoat and epoxy resin and it will not destroy plastic? Thanks