since there's no "create folder in project tree" script implemented yet I will share a little workaround with you.
The script "ResourceAddFolderFromLocal,Path" is normally used to add a folder from your local computer into the PB project.
If you not type a folders path into this script but only the name of a folder you want to create in your PB project, this script will do too.
Example:
ResourceAddFolderFromLocal,c:\coolux\content\testfiles >>> will add the folder testfiles which really exists in c:\coolux\content including all of it's content and subfolders into your PB project.
ResourceAddFolderFromLocal,testfiles >>> will add a new empty folder named testfiles into your PB project.
Maybe this is useful for somebody of you
Anyway a separate create folder script is already requested in the wishlist so this is maybe just a temporary workaround.