+1.
Opaque foils makes the life easiest....to avoid print to print errors(gaps) and other problems/fails of Gerber Edge Printers and Omega. Roland Colorcamm is a Junk but has some opaque foils(Gold, Silver Mate/Mirror, etc, etc) that are very helpful with a lot of works...
Regards.
Opaque foils I used.
Metallic Silver, All Medals, White form duracoat, black from geber and durocoat.
I think tahts all the opaque foils I used.