This is how we have managed the supplies for our five children for the past year.
We keep the cart in the mudroom (off the kitchen) and the kids bring it back and forth for use on the kitchen table.
The cart was a slightly damaged floor model from The Container Store, so it was already assembled and deeply discounted.
I dragged it around the store and tested all the boxes they had. Their clear plastic "shoe boxes" and "mens shoe boxes" fit perfectly, three abreast and three deep (on the lower two shelves).
I put a label on all four sides of each box. This allows the box to be returned in any orientation. Since the cart gets wheeled around, all of the labels and supplies are accessible/visible from both sides. None of the box lids are labeled, so there is no need to match up specific lids with specific boxes.
The whole set-up (minus the supplies, which were just gathered from around the house) cost $30 in May 2007.
This system has held up remarkably well, and the kids are able to keep up with it. The shelves look a bit bowed in this picture, but they were damaged a bit when I bought it. The sketch pads in the tote bag on the left hand side are quite heavy, and the cart has withstood much abuse.
(This is the same type of cart used in the GTDmobile.)