I finally bought proper containers for my tools and parts!
I wanted a solution that wouldn’t require me to put every part into ziplock bags when it was time to move to another apartment, so this is what I ended up with. The lids have sliding locks and ridges that help keep the compartments tight when the boxes aren’t sitting flat.
I made sure to buy a system that used little boxes instead of movable walls. In my experience, movable walls aren’t tight enough to keep small parts from spilling over into other compartments.
It took about two days to find all my parts and tools and put them in there, but it was worth it. No more digging for lost parts in random bags and containers.