This is a rugged box in a pelican case style.

Works really well as a small soldering case, I keep my iron and accessories in it. Those soldering inserts are separate inserts and not part of the box or files.  TS101 iron in case anyone was wondering :)

Dimensions of the inside of the box are showed in the drawing photo. I used some 3mm rod I had laying around and just pushed them into place and let friction do the work, though it would probably work just fine with M3 nuts and bolts. Just don't push too hard to get them in as the tabs aren't super thick.