Just to throw this info out there. These were created using the current version of Gimp on a Windows 10 Laptop. Using an old Wacom Cintiq 13″ Drawing Tablet. All of the “stipple” was done one dot at a time. Practically drove my wife crazy with all the “tap, tap, tap” of the pen hitting the display screen.
If anyone out there knows if a 100% free stipple brush for Gimp, or a Photoshop Stipple .abr that works in Gimp, please let me know. I have tried finding a stipple brush for Gimp. But the only free .abr I can find is not compatible. Or at least not setup correctly. And yes, it us possible to use Photoshop .abr brushes in Gimp. So long as they are configured correctly and installed to the correct folder.
I use to be a subscriber to both Photoshop and Illustrator. But have since moved to both Gimp and Inkscape. They work just as well, with similar setups/commands, and they are Freeware.