Borax is not a flux for copper or its alloys, wrong temps for one thing. Sal Ammoniac is a good choice for copper, but it is not needed for this application.
Cut not fold, clean clean then clean again.
For patterning, if our welds are good, any repose technique will work, hot or cold! but remember cold it will work harden,you WILL feel it start to get hard, STOP then, do not hammer even one blow more. We must occasionally heat to red, and quench to soften non ferrous metals. Also drilling for a birdseye, grinding slots for a ladder all work. Even twists if you are careful not to over work, remember the work hardening IS a metal stress.