Custom Foam Moldings for Crown

Hi all, As an alternative to creating replica plaster moldings, I’ve read that you can foam (or a similar material) moldings made, cover them in plaster and then install. The question is, can you get custom replica foam moldings made? If so, could you please point me in the direction of a person/company that can do this (note that I don’t believe they would be able to be done in wood). Any and all direction, advice is appreciated. Thanks in advance.