I found a Hefty 20qt Protect Gasketed, Hinged Lid Latch Box at Walmart that I thought would work well for my spools.
I designed this bracket to hold a 12" long 3/4" thick piece of aluminum tubing I had laying around. The box allows me to have 4 1KG spools side by side. Plus a dehumidifier. I added legs to keep the bracket from sliding down under the weight of the spools, and feet that fit into the grooves at the base of the box in order to prevent the bracket from sliding away from the wall. I also double sided taped the brackets to the walls so they don't slide back and forth.
Update: I added a V10 file which is 20mm taller than the first and angles the spool cups down to compensate for the -7 degrees of back tilt. The extra 20mm allows me to store the dehumidifier underneath the spools.