Sketch out designs for your garden onto transparent overhead projector paper. Or if you are competent with computer graphics, you may choose to create your designs on a computer. Then print a copy of each design onto transparency paper.
Stand an appropriate size of sheet metal against a blank wall to create life-size templates for 2-D sculptures.
Place the transparency paper onto a projector and project the image onto the sheet metal. Transfer your designs onto the metal by drawing an outline of the projected image. Use a tapered black marker. It's best to make a thin line so the marker ink is not so apparent when you cut out the design.
Put on a protective mask, coveralls and thick suede gloves. Cover your hair. Use metal cutters or a flat metal knife cutter made for that purpose. Starting at one end of the metal sheet cut along the marker line. Cut out any interior design segments using a sharp metal knife.
Use an electric sander to smooth out the cut edges. Buff along all cut edges until there are no sharp parts. Clean up with soap and water and dry with a lint-free cloth.
Attach one or more metal rings, depending on the sculpture size, onto the backside of the flat metal artwork. Wrap wire to create the rings. Use a liberal amount of epoxy glue to attach rings to the metal. Allow to dry overnight.
Slide a metal pole through the metal rings and mount the sculpture into the ground in the garden. If the pole is too thin, epoxy the pole to the rings while in a horizontal position. Allow overnight drying.