These are subdividers for the “Hart Stack System 3 Case Parts and Tool Box Organizer, Fits Hart's Modular Storage System” which you can get from Walmart at the link below:
There is a subdivider that turns a single compartment into two and a subdivider that turns a single compartment into three. These are great if you have small parts that you want to organize but need more compartments than the box has but don't need particularly large compartments. Like maybe small screws, or electrical components.
There is also a subdivider that creates two vertical compartments out of a double or triple compartment. This is good for storing longer things such as long screws or drill bits.
I noticed that some of my center components were actually a little bit smaller for some reason. For these, I scaled to 98%.
These parts were created using Solidworks.
The author marked this model as their own original creation.