This thing is huuuge!! I couldn't tell from the pictures just how gigantic it actually is. Even so, if you actually want to lay out all the pieces, it's not really possible to fit them all just on the removable inserts. I did a 1000 piece puzzle and ended up working on the puzzle in the main section and laying out the pieces on the two inserts, and then still ended up having to lay out the rest of the pieces on one of the flaps (which wouldn't have worked if I needed to close it up, so I tried to make it just the section I was working on next). I did try closing it up and waving it around, and all the pieces stayed put in exactly the same place! Overall, I'm happy with the purchase