I use a black, hard plastic, box setting jig, which attaches to a piece of 1/2" PVC. I have 2 pieces of PVC which are cut to my desired heights for switches, and receptacles. The jig, known as Depthset, was made by PC Industries, in Alton, Illinois.
Having worn out a few of these over the years, I'm in need of a couple of new ones.
My search has been unsucessful, as I believe the company has gone out of business. My question here to you, is do you know of any place which may sell the jig, or do you use any better such devices?