Gridfinity tray 4x2 (3u tall) with a hole shaped exactly to fit a very popular RJ45 crimp tool from aliexpress, sold under many different brands. There's a few variations but I'm fairly sure most of them will fit because the hole is slightly oversized (on purpose, for easy removal)

I also include a 4x2 (6u tall) bin with two asimetric divisions (roughly 60/40) that I use to store the RJ45 connectors and their rubber protectors, but there's nothing special about this bin, it was made with gridfinity rebuilt openscad.