Bench Mould mirrors are made using a method for running plaster cornices. The technique of making elliptical shapes using a trammel mould is described with almost mythical reverence by plasterers. A trammel mould is a slotted type of compass that allows you to draw an arc by moving the centre point as you go.
We make Bench Mould mirrors using this process in our studio and cast them in Jesmonite; A material much harder and denser than regular plaster with a marble-like finish.