Materials: in fact everything
Jet machining is the most versatile cutting technology. Just about every material can be cut. To give you an impression:
Metal: Aluminum, hardened steel, copper, lead, zinc, brass, stainless steel, titanium
Glass: armed glass, plexiglas, laminated glass, mirrors
Stone: ceramics, marble, plaster, porcelain, granite, bricks, tiles
Others: Polymers, composites, rubber, wood, insulation, printed circuit boards, foam.