The bottom is a simple wood box, held together by brads and glue. The upright is thin plywood pushed in to a slot in the base, cut with a table-saw.
The tool-holding brackets on both sides of the box are off-set from each other, so that both can be attached with screws through the backside. The one side has holes drilled through it for screwdrivers and similar tools. The other side is cut with a jig saw, to fit pliers, tin snips, and similar hand tools.
Larger and odd shaped tools fit in the bottom.
The box is narrow enough to not hit you in the knee while walking with the box. Because of the height of the handle, you don't have to bend over as far to pick up or set down the box.
The open design holds tools in place and in sight. No more digging to the bottom of a bag.
The box could be finished with stain, varnish, paint, or clear-coat, or simply left as-is.