Raw (solid) copper bracelet cuffs can be etched with ferric chloride, engraved, riveted and more. They are partially finished, and may require a bit of filing, sanding or tumbling, to smooth rough edges.
6" copper sheet cut to 1/2", 1" and 2" widths are perfect bracelets strips for average size wrists.
24 gauge is lightweight and easy to work with, but requires a second layer to be sturdy enough for a good bracelet. You can stamp it, and rivet or solder it to a bracelet blank of contrasting material.
20 gauge is a good compromise: it's still easy to stamp, embellish and otherwise work with, but it's also sturdy enough to hold up when worn as a bracelet.
14-gauge bracelet blanks are flat, and pre-cut to 5-3/4" (for small/medium wrists), 6-1/4" (for medium/large wrists), and 7". The ends are curved, and the blanks are ready to customize!