Junk metal does not mean rusty metal. In fact, most sculptors have a preference toward clean metal with no signs of rust. Rust can be removed from metal by means of a grinder, but clean metal can be used right away.
From the high-quality metal alloys found in rings and pistons to the funky curves of sheet metal used in fenders, the discarded automobile is a proverbial "gold mine" of used metal.
A metal sculptor must depend on his welding skills to create much of his work. Fine art welders have a choice between oxygen-acetylene welding equipment and the more industrial arc welding, which can be used for large projects.
Not all sculpture is three-dimensional. Bas relief involves creating a two-dimensional plane of sculptured forms (not always metal) that is very similar to a plaque. Bas relief is never completely flat like a painting, but has depth and realistic form, like a plaster mold of a human face.
Sculpture does not always involve the use of metal that has been completely altered and shaped, as if it were plastic. Sometimes, found metal objects like spark plugs, metal washers, pieces of wire and bolts can be incorporated into a sculpture in their original form.