And, of course, when you buy Legos they come in sets. And when you have to put away your Legos, you want to keep the sets together. And if you want the sets to stay together, you need to have separate containers for each set. That is a bit impossible.
Right now we have standard Sterilite containers (Sterilite products are made in the US.) Each holds, I'd estimate, 10, 000 Legos. And we have about 5. And the kids know every piece they have.
I have seen the Lego containers sold that sort the sizes, but they seem too small for what we need. They also sell Lego Brick boxes, the boxes themselves look like bricks, Lego Head storage boxes, and of course, plastic drawers. We need transportable, stackable, not-too-large-not-too-small-not-too-expensive solutions.