I built this browser tool which lets you quickly generate 3D printable boxes in your browser. It's pretty useful when you are rapidly iterating a design and need a box with specific parameters for internal capacity or external size without the effort of opening up CAD software.

It uses Three.js for rendering, and runs entirely in the browser (no server necessary).

It works in inches, mm, and also Gridfinity, which is a standard for making 3D printable storage units which stack nicely and fit along a 42 mm grid. It uses internal units of 10 nm, so that 100,000 are exactly one mm, and 2,540,000 are exactly one inch.

I have validated the numbers against the Gridfinity spec, but I don't have access to a 3D printer right now. I would love to hear what people think of it so far, or if one of you has a 3D printer nearby, I would love to know if it actually works.