Well, Sarah had an idea for me and it was something I was already thinking about!
Here's a clue for you.
That tells you a lot, doesn't it?
Here's another clue:
Hmmm. Now we know it's made of wood at least.
I made three of these boxes today, and did you know that there are 112!!! cuts in the joints for each one of those boxes?!!!
Look back at the first picture now and you can see that it's going to have a curved top.