What I wanted to do was use these blue BookSource bins we had in our school. Each bin holds about 4 spools. To start, I did a quick sketch with a few dimensions of the bins. The basic idea is going to be to use 1" furring strips to create ledges or shelves for the bins to slide into.
I did a quick mock-up of the design in #sketchup to layout the cut list. I spaced the shelves so that there was enough room for the spools to fit and that the entire cart would fit under our tables. The space below the tables measure 24". This was one of my design constraints. I wanted it to hold as many bins and be able to fit under the table. The following design is what we came up with:
For build-to layout and drawings, I exported the model to #layout.
The build is made using 1" furring strips, 5 mm Underlayment RevolutionPly - available at Lowes, and 1-5/8 in. Rubber Light Duty Swivel Casters from Harbor Freight. The RevolutionPly is simply amazing to work with. It has a really nice finish, and with a little polyurethane, it ends up looking amazing.
In the original design, I planned on using an extra layer of 5 mm ply in between the 1" furring strip. When building it, I forgot to do this. As it turned out, I didn't need the extra width.
A second change that I had to make was to flip the design upside down. I added an extra layer of a furring strip on the bottom edge to screw the wheels into. This interfered with the bottom edge of the bins. Thankfully, the top side was set deeper -- so, simply flipping the cart upside down fixed this problem.
I really like these carts. I think that we could use several more of these throughout the school and our space.