Speaking of MDF vs. wood, do you have to take wood movement into account? I’m sure those little cubes don’t expand very much, but it looks like they fit snugly into the box.
I thought you sold your puzzles. If you’re giving them away, I see why you prefer MDF for fiscal reasons (in addition to the uniformity you mentioned).
I like to use lots of scenes in my models. I don’t take care to add clipping volumes around them. I suspect more than one viewer has opened one of my models and hit the zoom-all icon and concluded I’m a total idiot when they see little clumps of geometry spread all over the place.