For most metals, 14-gauge would be too thick for metal stamping, but because aluminum is a soft metal, 14 gauge is a good compromise between stampability and bracelet durability.
Copper isn't quite as soft, so 14-gauge is a little tougher to stamp. We recommend smaller stamps, or annealing the blanks before stamping with larger stamps.
Both materials can easily be bent on an oval bracelet mandrel or using the E-Z Bender tool. They polish up beautifully!