I made simple drawn plans on paper. Using 1/4" fiberboard from Home Depot at roughly 54"x23", I cut, glued and nailed 1/2"x3/4" quarter round (the wider portion laid horizontally) at the edges of the board, with the curved portion facing outwards. For most of them, I cut and laid 5/8" thick, 12 oz. Dacron Fiberfill batting three layers deep into the space between, using spray adhesive to fix it to the board and lightly secure the layers to one another.
Several panels were wider (31", as I recall), specific to their location. Also, for the panels behind the speakers, I used 2" thick recycled denim insulation rolls (one layer).
I carefully cut and stretched the fabric, stapling it around the back of the panel. I actually had to redo this on several panels, because they appeared to have "cellulite." I loosened the stretch until it was smoother.
I added mounting hardware on most panels, although I was able to use simple eye hooks with picture wire and found that much easier on my last panel or two. I wish I'd done this with all of them!
I can share more later, if you'd like.
Cheers,
Juan