DynamicPaintbrush is a dynamic process that allows us to define a custom brush and use it to paint over any view (opened image) in PixInsight. It has been designed mainly for editing masks, although it can also be used as a simple markup tool.
The first release of the DynamicPaintbrush module is now available for download for Windows only at the moment:
Versions for macOS and Linux should be available later this month. No date for a BSD version at the moment. (DynamicPaintbrush is OS-dependent because it's a module, not a script).
DynamicPaintbrush is being released as shareware, with a 30 days free trial, and a registration price of less than five bucks (I think that's reasonable - there are free solutions outside of the PixInsight world, otherwise).
PS: It may have crossed some people's minds, but this is not an April 1st prank! Hopefully my pre-announcement a couple of weeks ago helped when reading the subject today