This was designed to hold up to 3 spools of White River fly fishing tippet material with a center hole diameter of 5/8" (15mm) and height of 10mm each. Design is based on an Umpqua version I saw at a local fly shop for an obscene $20. If you are a 3d printing/fishing guide or something and want a version that holds more spools please message me and I will upload a larger version.
The author marked this model as their own original creation.