What you want are:
(3) pieces of wood that are the same width
- (2) of those pieces should be the same length (ends)
- (1) will be the box bottom
(4) pieces of wood that are length of your box bottom PLUS the twice the thickness of the end material
- (2) should be thin
- (2) should be wider
How long and how wide you want these pieces to be will depend on your needs and materials.
As for my box, the measurements are, in inches:
Bottom (1) - 8 W x 13 L
Ends (2) - 8 W x 12 L
Sides, upper (2) - 1 W x 14.5 L
Sides, lower (2) - 3.5 W x 14.5 L
The dimensions of the sides can be played around with the most to reduce waste. Having two rails for the sides isn't even completely necessary, it just makes clamping possible and reduces weight slightly. Cutting the corners off the ends isn't necessary either, as it's mostly done for aesthetic purposes. I cut the corners because...well, that's how toolboxes look like. It's a classic shape that's easily recognizable and has stood the test of time. I feel it's what separates a toolbox from a box with tools.
With that said, the corners can be cut almost any measurement. I used the golden ratio
as much as possible. Mathematicians/artists/architects have been obsessed with this ratio for thousands of years and say it's more aesthetically pleasing, so why not use it for an otherwise arbitrary cut.
If you decide to cut the corners using that method this website
is very helpful. My golden ratio measurements are on one of the pictures.
The handle should be a few inches longer that the total length of the box (the length of the sides). I cut my rebar pieces to 16.75" to give me about 2" of overhang, which is all I needed to clamp my drill case, but I'd suggest anything from 3"-6" would be good. You should follow your needs.