Talent comes from a youth well spent.
Is the copper then covered in a surface or just etched.
Here's the process:
1. Use original pick guard to make a template out of plastic, plexiglass or similar
2. Use the template to cut out the shape using a router
3. Use the original pick guard to drill the mounting holes in the copper pick guard
4. Sand the copper with 220 grit then clean with acetone - always wear gloves when sanding and cleaning to avoid getting skin oils on the copper
5. Place the copper on some small wood blocks inside a large enough tupperware container
6. Press whatever you want to use for a semi masking material - I used hibiscus leaves. My brother used onion slices
7. Put ~1 tbsp of salt and ~4 ounces of ammonia in a spray bottle that can spray a fine mist. Mix by shaking.
8. Spray a fine mist of ammonia / salt on the copper. Try to avoid pooling - you can dab the pools gently with paper towel to remove them
9. Install the tupperware cover and let it sit for ~6 hours
10. Remove the copper pick guard and let it dry in air for ~6 hours
11. Gently rinse in a bath of warm water
12. Let the pick guard fully air dry
13. Spray 4 to 6 coats of clear, lacquer spray paint or brush with clear nail polish. I used Rust-Oleum clear lacquer spray finish and did 5 coats.