After some tests with plaster and silicone rubber, the final shell was obtained by pouring epoxy resin into moulds previously made with semi-finished methacrylate products. The holes and the housings for the magnets were obtained with some inserts.

A belt transmission mechanism guarantees the correct winding and unwinding of the film when the single knob is turned. The rotation is helped by polypropylene discs placed on the friction areas.