I used 18 gauge sterling silver again but 20 gauge will work well too . You need 2 circles in the same size . I have a disc cutter for that but you can also cut by hand. Draw a shape on one of the circles ( I drew a flower) drill a hole to feed your saw blade through and start cutting . I have a 6 inch saw frame and I mostly use 1/0 saw blades ( from riogrande.com ). After cutting out your shape quickly sand down the 2 circles so its easier to solder.
Solder both circles together and make sure you have no gabs in between. Quench in water and then put in a pickle solution to clean your silver from the oxidation. Punch a hole for the jump ring or bail.
After the pickle bath dry your pendant and start polishing . ( I use a flex shaft with bristle brushes ) Add Patina ( lifer of sulfur ) and polish again carefully so that the inner flower stays dark. Add a jump ring and a chain and wear proudly . :)
Again I also have a shop where I sell the things you see at www.nicilaskin.etsy.com
nici