Cast: Typically is unbendable, rough to the touch, and cracks under pressure. Cast is used in motor blocks and housings, transmissions and small engine parts.
Clip: Unpainted sheet, new production materials 1/4" or less.
Extrusion: Typically found in screen door and window frames.
Old Sheet: Pots and pans, ladders, and radiators.
Painted Siding: Exterior aluminum siding on houses.