These baseplates fit the Harbor Freight medium sized small-parts organizer (this one). I included two variants, the minimal baseplate and the skeletonized version with magnets. The magnet holes are sized for press-fit without needing glue.

I'm crediting this as a remix since I took the dimensions from the original, but then I recreated it in onshape. This allowed me create it as a single piece, add padding in a couple more places for a nice snug fit, fillet the corners, etc. I also removed some of the height from the skeletonized baseplate compared to the openscad version. I use the openscad baseplates on my desk where I want some extra weight to help hold them in place, but that is not needed here and we can save filament/time and gain a few more mm of height for storage bins.

I also made baseplates for the “large” organizer: https://makerworld.com/en/models/32684