Spool holder (Tinker Toys for bigger boys)

As my handle suggests I work at a hardware store, so for things that need durability I use the available options.
Here's my quick easy solution for a spool holder.
Currently it has space for 14 spools of any size spool I've run into.
The basic version I put together in the first picture is two 6" corner braces, two 6" mending braces, a 1/4" x 12" threaded rod (it's actually a 10-24 in the picture, it was just the easiest to grab.) Two nuts and two wingnuts hold the rod to the braces and it c