The second method is more elaborate.
Color Space in
Gray Level and
Fill with: white.
→ with, for example, a width and a length of 35 pixels
and in the advanced options a
Zoom on this new image to enlarge it and draw on it with a black
Save it with a .gbr extension in the directory
In the brushes window, click on the button
And your marvellous brush appears right in the middle of the other
brushes. You can use it immediately, without starting GIMP again.
Steps to create a brush