The puzzle is made from a kind of resin (if you know the material used, please say it in the comment section) which looks like stone.
When you move the puzzle, you can hear some things ratling inside but once solved you will not see what's inside because the drawer cannot completely get out of the box.
The name of the puzzle is a hint about how to solve the puzzle, and I am sure you can guess easily where to push :)
The puzzle is not very difficult and it did not take me long time to understand how to solve it. It can be solved repeatedly (it can still take you some seconds).
I wish it had been a bit more difficult but I like it though. Again, I feel a bit frustrated not to be able to see the internals nor to have a picture of them (if you have it, please send it to me)
Have you ever tried to put something inside the drawer?
A nice puzzle in any collection!