Automatically appends the size to your folder's name.
e.g. SomeFolder (1.20 GiB)
Just grab Python from http://python.org, Python 3 specifically
Then run python3 main.py, in the folder you want to rename.
Further instructions for easy-use (e.g. right-click) will follow.
A friend of mine had the idea, I thought it was cool. Mike, if you're reading this contribute! :)