The ULTIMATE Organization for Your Snap-On ToolBox - Tool Grid: Part 1
These are 90 degree holders that can be used to make a U-holder, diagonal holder, or makeshift box. I've also found myself using these holders in
Tool Grid Corner Holder
Toolgrid (@mantis.toolgrid) • Instagram photos and videos
Finally gave in and bought into the ToolGrid : r/toolporn
Toolgrid well worth the investment : r/toolporn
Tool Grid Socket Holder – Obsessed Garage
This Old Garage - Northeast Region, Porsche Club of America
Tool Grid Socket Holder – Obsessed Garage
Toolbox Giveaway – Obsessed Garage