First I constructed a piece fabric (Alisa Burke's Sew Wild again!) using torn scraps from my stash--which I don't use much anymore because I paint or dye most of what I need. The background is old plaid shirting (yikes!) placed atop a piece of craft felt with a bunch of other bits scattered (strategically, of coarse) across the top. After pinning everything down, I took it to my wonderful Bernina and began sewing. That was the really exciting part--I simply started free-motion stitching (both zigzag and straight) until every edge was sewn down and every center lightly "quilted." Love it.
This time, for my "collapsible" version, I used 5 individual pieces of fusible interfacing for the sides and bottom. The photo above shows the box upside down with straps (sewn onto one side and velcroed onto the other) crisscrossing the opening. The bottom, pictured in the foreground, will simply slip inside and sit on the straps quite securely. By the way, the inner sides and bottom of the box are covered with a fabric posted earlier.
I also constructed a simple divider using two additional squares.
And here's the final box. The whole think can be taken apart and stored (or shipped) flat.