I too, stack my parallel clamps and pipe clamps outward from the wall. Each slot holds a different length clamp and holds 8 per slot. My "A" shaped brackets were made from 2 X 4 and 2 X 6 framing lumber with them made in the shape of a shelf bracket, but with a 45 degree brace underneath. Biscuits and glue were used for their assembly. I made a very heavy duty French Cleat system out of 2 X 4 to attach these to the wall using 3 1/2" screws through the French Cleat and into the wall studs. Each "A" bracket is also screwed to the French cleat board after it is positioned for the needed space from the adjacent bracket. 48 + parallel clamps in one place is very heavy, but then I also have about 20 + pipe clamps there too. This rack system was built about 17 years ago because I was running out of shop wall space and it has been trouble free since I began using it. Below the shorter parallel clamps I have places to store "C" clamps, "F" clamps, and band clamps, so my total wall space for clamp storage is only about 40" wide. My 2 screw type wooden clamps of various sizes are all clamped to the edge of a window frame. I only have about a dozen of them, so if I get more I'll need a bigger window. The flat aluminum edge guide clamps are all hanging in slots in a kind-of shelf bracket that's attached to the relatively unused 4' wide barn style door. The more often used 2nd of these two doors has two Workmates hanging from brackets on it, one above the other.
Charley