Supplies needed for sawing your own metal shapes:
Jewelry's saw frame
How to saw metal:
Adhere your design to sheet metal with rubber cement and let dry.
Insert saw blade into saw frame with the teeth pointing out (away from frame) and down (towards floor). Make sure you have the blade in there good and tight a loose blade very quickly becomes a broken blade! Tension is key.
Hold your metal in place on the bench pin with your non-dominant hand.
Hold the saw frame between 90 and 45 degrees to your metal and start sawing. You are only sawing (removing metal) on the down stroke, but try to keep the sawing motion smooth and even on both the upstroke and down stroke.
Follow your design! It takes practice, but you'll pretty quickly learn how to maneuver your metal and/or saw to follow curves. Blow away the shavings every so often so you can stay true to your pattern. If the blade seems to be catching or it feels jerky, check your tension and/or apply a little lubricant to the blade.
Moving too quickly, especially when changing direction, is an easy way to break your blade. Smooth and steady wins the race. One of the most difficult things at first is not pressing too hard with the hand that's holding the metal down. Hand cramps hurt, so take frequent breaks and be conscious of what you're doing. It doesn't take much pressure to keep your metal in place. It does, however, take that V-cut bench pin. You will (er, I did) break lots of blades and have tons of problems if you try to hang your metal off the edge of a table rather than supporting it on both sides of that V.
It is always a good idea to wear safety glasses while you are sawing. Everyone breaks blades, and you'll notice yourself getting your face closer and closer to your project. So again, take frequent breaks and also be sure to set up your sawing station at a height that is comfortable for you.