These are a few ideas on finishing metal. I did these on a headband so they are more cosmetic than practical.
Made at TechShop Chandler www.techshop.ws
Step 1: Stencil and Etching
I used vinyl to make a few stripes in my headband. I pressed them down firmly to not so firmly to test how easily the vinyl would peal up in the sandblasting cabinet.
Step 2: Sandblasting
The picture is hard to see but it's me holding my piece in the cabinet spraying. I suggest spraying perpendicular to the vinyl. If you spray from the side you risk lifting up an edge and that doesn't look good.
Step 3: The Reveal
You can probably tell which stripe of vinyl I was really thorough pressing the edges down. I don't think it helped that these were pretty thin pieces either. I've done this on glass with a much wider vinyl stencil and that seemed to help. Long story shirt, be thorough laying down your stencil and press firmly getting any air bubbles out.
Step 4: Deburring Wheel
You can use the deburring wheel to smooth out edges as well as finishing metal! If you thought your project was way too shiny or just preferred a different finish you can use the deburring wheel. The first picture is of some stainless steel that originally had a mirror finish. It still has some shine despite that picture. The 2nd is of a piece of copper, it gives a sort of matte look.