Single Fridge Magnet - Ammonite B-sides and Abandoned Tracks Each magnet is "bonded/coldcast brass" - brass powder suspended in a polyester resin. Each magnet is handmade and hand finished.. The process involves carving an original out of clay, wax, or plaster. A silicone mould is taken, and the the magnets cast from there. Made especially for New Model Army at the 'Gelert Design shop'.