This is a basic spool holder which uses a removable dowel/metal rod as the baseline holder for in-use filament on any printer. I have used a similar system I designed for years and it held up fairly well, but with a recent house move I decided to make something more permanent. 

For the assembly, all you'll need is to print both RHS and LHS parts along with the "washers". Two M4 bolts and nuts required to properly mount to garage shelf. This is overkill, but I typically don't change my filament rolls too frequently so there's anywhere from 5-10kg sitting on the rod at any given time. The bolts are much stronger than PLA and help prevent it from breaking. 

The washers have an indent with a diameter 0.6 mm larger than the aligning protrusion. When tightening the bolt, these two parts should click together and remain rigidly locked together.

Garage shelf compatibility

Upper diameter: Any

Inner-diameter: 6 mm

Gap between slats: 44mm

Measurement example