Update: another tool is in - Invisible Plane.
Select a surface and click Invisible Plane, and the tool creates a plane from it, automatically placed on a tag. You can then draw lines on that plane no matter where you click, so after rotating the camera they are still on the plane instead of ending up somewhere else. The plane can be turned on and off with its tag, or deleted completely.
Video: https://youtu.be/GU133K7tTgg
Short: https://youtube.com/shorts/YPrrJx6pbM0
I'll keep adding the rest of the tools one by one. Feedback is welcome, especially on which tools you'd like to see next.