We found a possible "candidate" for the new storage box. It tested good. According to our experience it's a really good quality plastic box with lots of useful features: e.g.: click-on lid locking system, 2 levels for storing...
Ideal for storing and separating the smaller pieces, and has spacious place for even the 300 mm beams. Here are some photos to give a little hint how it looks and how the MakerBeam / OpenBeam items fit in it.
We still search a bit further, but maybe you will meet with this one in our product range.