Print a Left Hand Side & Right Hand Side corresponding to whatever diameter rod you have. I used a curtain rod that was adjustable in length so I could grow/ shrink the spool holder as necessary when installing on my wall. My rod had a 0.75" dia. on one end and a 0.625 on the other since it was a telescoping rod.
Put 3 screws into each bracket and you're done! Very clean and easy way to store your filament spools.
Needs a "large" print area. 7.4" x 7.4" minimum.