made this to hold a roll of string trimmer string. I have a lawn care business so I get the big rolls and wanted something to store it and still use it daily. 

the rod is 7 inches but should be easily adjusted If you need. the rod sits in the slots and holds it in place. I would do 25% infill for the rod and PETG works best if you're going to store it in a trailer or shed where it gets hot.