Print your own F-Clamp storage rack brackets!  Within the downloadable file are an assortment of F-Clamp bracket sizes.
 
Large - Houses 6 F-Clamps
Medium - Houses 4 F-Clamps
Small - Houses 2 F-Clamps
Single - Houses a single F-Clamp
 
Print these in an assortment of sizes to suit the space you have.

Included are the .STL files that you can import into your preferred slicer program to print your own adapters!

You'll require some additional hardware to mount your bracket (screws or bolts).
 
Suitable to be printed using most standard filaments including PLA/PETG.