Awesome

Stamp Tool (Extended)

This is similar to the existing Unity Terrain Stamp Tool, but which supports special mouse handling and other features.

Features

Special Mouse and Keyboard Shortcuts:

brush resize: ctrl + mouse drag left/right
brush rotation: ctrl + mousewheel
stamp resize: ctrl + shift + mousewheel

Stamp 3d Preview

Screenshots

Inspector:

inspector

Example (resize brush, resize stamp, rotate brush):

example-1

Example (3d preview)

preview3d

Requirements

Unity 2018.3+

Update

Time passes by ... Unity added rotation and scaling to their a later version of their Terrain Tools

Credits

Full credit and a BIG THANK YOU(!!!) to the very skilled and most awesome developers at Unity who provided the Terrain Tool Samples for free for the community.