Insulating the box from the hanging locker is actually the easiest part of the project. I did it a while ago to get rid of the condensation on the locker wall. I’m now doing the rest of the box and it is a lot more work.
In the locker figure out where you are going to drill the holes. Put vertical strips of 2″ wide blue tape and drill the holes in the center of the strips. Drill 3/8″ diameter holes into the void. I spaced the holes about 6″ apart. Start the foam at the bottom and work up. The foam will expand out of the holes so be prepared to wipe it away if it looks like it will go beyond the tape. You will learn to get it so that only a small tails comes out, leave it. After it cures, trim it off with a knife,