I don´t kno about brands since you live in the usa and it´s completely different...but i can say, use the foam in a ventilated area, and wait. Wait at least 24 hours before you touch it or modelate it with a razor...if you don´t the inside will be fresh and you´ll mess it all up. Oh and spray a bit of water before putting the foam, it helps to spand.
I haven´t used epoxy, but a friend of mine did and didn´t get good results...too complicated. But you may have luck with it.