I’ve been working on my incredibly stupid plan to organize my tools by boxing them by type and hanging them on the wall, so I got a bunch of the littler, non-folding Trusco toolboxes. The only problem is that they don’t have divider options like the bigger ones to. The solution is 1mm styrene sheets! These are used in model-making, but they seem sort of under-appreciated for tool storage.
I get my styrene from Evergreen Scale Models, since they have the fun box sections and so on. All you need are the sheets, an adhesive like Weld-On 3, a little brush, and an X-acto knife. I make them pretty snug, then secure them lightly with just a bit of Super Glue, so that they’re easy to rip out.