First a pattern must be made from the original design. Usually, I draw the bell as a finished piece, then develop a profile of the bell. The profile drawing is then transferred to a template which is used as a sweep. Rotating the sweep around setting plaster creates a pattern which can be used as a die to make other pattern copies. As many copies are mounted on a pattern board (called a match plate) as will fit within the molding frame (flask).

Designing and sweeping a bell pattern