They were produced in moulds using gypsum plaster reinforced with scrim — a course, open weave cloth — with a backing of laths and ribs to strength the piece and provide fixing points.
Fe'u cynhyrchwyd mewn mowldiau gan ddefnyddio plastr gypswm wedi'i atgyfnerthu â sgrim - defnydd â gwead agored, bras - gyda ffrâm o ddellt ac asennau i gryfhau'r darn a darparu pwyntiau gosod.