Can Seat Foam Be "Fabricated"?

The original foam for the bucket seats in my '65 Valiant and Barracuda Formula "S" is disintegrating. Does anyone know if the only option is purchasing a reproduction online seat foam or do upholstery shops have a way of making their own? Thank you.
Upholstery shops glue and form their own seat foam. They use a tool like a electric knife to form it.