I did not know this... how low/high. I think I have a 60Amp 5v PSU.
Most of the sources I have read recommend a 6-12V PSU, like what car battery chargers use. though the process should (in theory) work at 5V, it will be much slower. You can use a computer power supply for this.
metallurgy there might be small holes on the surface I think. to make this kind of stuff stamping is the best way, but... it's usually for big ammount like ipad casing.
It would give it an excellent matte finish, though. Also, there are ways to make it closer to fully dense, liquid phase sintering for example. Your real problem would be the shrinkage while sintering. It's pretty easy to calculate this, though. For stamping, I would worry about internal stresses in the metal. It's what... 2 inches deep? No: CNC looks better.
Hmm, I wonder if some phantom-compatible cases could be made... I know I'd want one.