Draw an initial concept on paper, laying out the design of the sculpture. When designing the piece, keep in mind that the bottom pieces need to be strong enough to hold up the top pieces. For specific shaped metal pieces, draw the shape on paper and trace it on to the metal before cutting. If you work with scrap and don't want to have a plan, experiment with the metal parts until you get a result that pleases you.
Shape the metal to fit the parts you need for your design. Sheets of metal can be cut with a cutting torch, following a pre-drawn design. Metal sheets can also be bent and hammered into a three-dimensional shape. Place the sheet in a vise to hold it in place as you form the metal. Smooth the cut edges with a grinder.
Treat any scrap metal to remove rust or smooth out rough spots. Use a sander to scrape away impurities on the metal surface. Polish the metal with polish formulated for the particular type of metal to make the pieces shine, or leave them as you found them for a rougher look.
Weld the metal pieces together to make a finished sculpture. Smaller sculptures using lighter metals can be soldered rather than welded. If you want to avoid heating the metal, use wire to bind the parts together. When the sculpture cools, you can add paint or glue on non-metallic elements such as beads, shells or cloth if you wish.