Mystery little box thingy.

I keep trying to picture what this case might have been used for. With the shape of the inner piece with the hole, it almost looks like it could have been set up that way so stored items could drop through the hole. Were coins that small in those days?

Of course, that wouldn't explain why it's so hard to get and keep it open. Could it be the spring wasn't supposed to be that tight?

 

I think it's missing a part.

 

would a lens make sense ? linen tester/weaver's glass etc.