could use around 10 (4’x8’) sheets of 1/2" or 3/8" foam core. Looking for 5 or 8 pound.
Will be used with polyester resin.
I think polyester resin isn’t supposed to be used with foam core because it will melt it. make a test panel first.
Polyurathane foam is fine with polyester resin
so is pvc foam and san, and pet.
actually the only 3 cores that melt are eps, xps, and undercured (sh!t quality) pvc (klegecell brand…)