I've finished the Explosion Box! - and in the nick of time, too. We're taking our friend out for lunch tomorrow to celebrate our mutual belated birthday together, and I'm giving it to her then.
Because I'd only taken photos of the "work in progress" and not in an ideal setting, I've re-taken photos of the finished box in daylight and with a better background, which really show it off better.
I have also made a video: