Custom-Size Stackable Toolbox Organizer

Make your own - size, free, no signup - chamfer

The problem: 

Gridfinity is great, but it only works in 42mm grid units - it doesn't help when you're trying to fill the oddball tray in a Ryobi/DeWalt/Milwaukee stackable tool box. Those trays don't line up to any grid.

This bin: 

Sized directly in millimeters. Tell it your tray's width, depth, and height, how many compartments you want, and whether you'd like square, rounded, or 45°-cut corners - it generates a fitted bin instantly, in your browser. Bins with the same footprint stack securely: each one has a foot on the bottom and a matching socket on the rim, so they interlock instead of just resting on top of each other.

This upload: 

a 120 × 108 × 64mm bin (for Ryobi toolbox), split into 2 side-by-side compartments (~58 × 106mm usable floor each), with 45°-cut front corners for easy fingertip access to small parts. Sized to drop into a typical stackable-toolbox tray slot - check your own tray first, dimensions vary by model and generation.