Guitar ReRanch would probably be your best source.
hi Greg- I use to do custom painting on hard body guitars and I had an automobile paint supplier that had flake that I use to mix with clear laqure and it worked out very well- so maby that can be a possible thing that you can try - HOWEVER
if you try it then do it on a spare piece of material before you lay it on the finished product- peace, Donald
I think Gibson used Crescent Bronzing Powders. Many on the mylespaul forum say it's Crescent Bronze Extra Brilliant Greengold #256. I've seen others say that it's a mixture of two colors. You can order a color sample card from Crescent. Look at their site and scroll down:
Here's a guitar done this way:
Here are some threads at mylespaul that could be helpful:
I second Crescent as a first shot.
Hi Greg-- good luck with your project and do a good job-- peace, Donald