Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Prefab Brush Free.
Prefab Brush v1.4
What is it?
It’s a prefab and mesh placement tool that simulates the use of a painters brush, allowing you to rapidly paint objects and create unique looking environments in seconds.
What benefits does this offer?
Refer to the video for a full demonstration.
Video Demo and Tutorial: Here