These are parametric Gridfinity bins for storing breadboards, created in OpenSCAD using Gridfinity Rebuilt in OpenSCAD by kennetek.
The OpenSCAD model depends on included third-party library code. Download and unzip libraries.zip into the same folder as breadboard-bin.scad.
The breadboard size and number of breadboards are both configurable in the OpenSCAD source model.
In the uploaded model renders, the 4x4 3-breadboard holder is sized to fit 3 breadboards with 4 total power rails (instead of 6).
The author remixed this model.
This uses my remix of Gridfinity Rebuilt in OpenSCAD to create breadboard bins.