One big difficulty in trading is the hauling of items. Trading low value bulk stuff if not worth it because of the effort to do all of the moving.
A slight improvement to some previous idea of crates would be shipping crates.
You could build a shipping crate with some boards and such. Then you could load any amount of one specific item in it, such as blueberries.
You could not take items, you could not move the crate.
But you could seal the crate, after sealing, you could move the crate, but not take items from it or put items in. You could see how many blueberries are in though.
Then you could open the sealed crate, which would again make you unable to move the crate, and you could only take items out, not in. And when items run out you could disassemble the crate completely.