Do you have a Home-Depot husky heavy duty garage shelf?
Then this light weight, but very strong adapter does the job combined with Repkord's Open Source Spool Holder And Storage System! It was made to mount on the side/end caps and give you space to add more storage to Husky HD shelf.
You'll be able to add 8 rolls per rack with this 24" setup and if you have your printers on the shelf then you can feed it with ease too! I left the original holes in case you want more security, but once every is clamped down and spools are added its not moving. Printed everything in PETG-CF so tiny tree supports are needed for the locking lip.
Remember very low fan speeds are needed. most of the time the part fans are turned off!
Print time: 2h
Printer: X1C
Nozzle: 0.6 HS
LH: 0.24
Filament: IEMAI PETG-CF or better
Wall loops: 4
infill: 30%+
Top and bottom layers: 3
Supports: Yes under the lip only