Cut a copper sheet into your desired shape and bury it beneath the squishy chips making sure there is plenty of contact between copper and chips. Allow the copper to sit in the chips overnight. You’ll be developing copper sulfate and chloride salts of copper on the surface.
The next day, you’ll have something like this including a little chip goo. Let the pieces dry and gently brush off any residual potato chips. Then seal up your pieces with a clear sealant. I used some clear nail polish. Once the sealant has dried, your potato chip patina is ready to go on your next jewelry project!