Originally Posted by flybytaco
make your mold out of styrofoam and when it cures pour acetone in it and melt out the mold i've seen it done for speaker enclosures idk about a gas tank
Polyester resin will melt styrofome in a new york second! Epoxy resin won't, but polyester won't stick to epoxy while epoxy will
stick to polyester! For proof of exp with epoxy resin see the transom of my afforementioned duck boat (self designed and built stitch and tape 14'-10" pirogue) in pic of my bike in this thread. http://motorbicycling.com/f41/falcon...ild-18324.html
Also, from my limited exp in custom mold making, there is a special wax called release agent that you can apply directly to your old tank so you can lay up a master mold. Pop out your "slug", and lay up your new tank in the master (again many coats of release agent). Then glass the halves together and coat the new tank with epoxy inside and out.