Adding patina to brass and copper: Put sawdust in a small resealable container, pour white vinegar on it, and mix until it's paste-like. Submerge your metal in the wet sawdust, seal it, and set overnight (or just a few hours in sunlight, which speeds the process). Let the pieces air dry and brush off any excess sawdust with a soft brush.
Make the two sides of the locket case. Sweat medium solder onto one side of each bearing plate. Place a bearing plate, solder side up, on a tripod stand. Place a dome on top of the bearing plate. Solder the pieces, heating evenly from below and above using a large, soft flame. Repeat with the other pair. These pieces are the two sides of the locket case. Prepare the locket case for a hinge. Use masking tape to tape