This is best described as a mechanical 'shaker maker' in my opinion. You would place your runny plaster of Paris mixture inside a two-sided mould (1 x skull, 1 x mummy, 1 x warewolf), and the mould is then placed inside a perspex ball, (a bit like one of those hamster balls you get these days). This is placed upon a machine with three wheels running, so the ball spins and mixes the plaster. Once it's done, just let dry and then paint your monsters! Happy days! You would then either swap or sell your creation for all sorts of school-boy tat!