Paint with masks

This is in 3.0 ....

Use Ctrl and paint ... to paint a mask ...
start to draw on the model, not on the canvas ...

Hit Tools/Create Alpha ...

Your new alpha loads ... see the Alpha palette ...

Drop in Projection Master ...

Paint loosely in PM ...

Drop out of Projection Master ...

Ctrl drag on the canvas a little box to clear the mask
to see the result ...

That’s it.