I have several of these Kobalt heavy duty storage bins. I wanted a better way to have a stable divider for them than just to jam a piece of loose plywood in channels. So I took basic measurements and design a key to fit in the divider channel allowing you to place a stable divider in the box to better utilize the space. The key is roughly 8 inches tall and 1 5/8" wide. The divider key still allows the boxes to lock together stack.

I used default, generic, settings for the filament out of Cura on my Anycubic Kobra Max. I positioned it flat across the print bed and did not need any support materials except for the magnet channels on the back side. I superglued magnets on the Bin Divider Key and then on the storage bin itself just to hold the keys in place when there wasn't a divider between them to hold them in place.

Print time each time I did it at 20% infill was 2hrs 15 minutes, again using generic settings(speed, feed & temps) from Cura.

I designed this in SketchUp from measurements I took from my Kobalt storage bin. I noticed that my bins I have would vary quite a bit near the bottom in the channel so that is why there is a kickstand near the bottom instead of the key going full size all the way to the bottom. It would allow it to fit better across all the different Kobalt bins I have. SketchUp file uploaded for your downloading pleasure.

This is the bin I reference: https://www.lowes.com/pd/Kobalt-Kobalt-Stackable-Crate/5001974065

These are the magnets I used: https://amzn.to/3JRQf48