I have finally gotten around to creating some custom cross hatching brushes for GIMP. I am quite happy with how they have turned out. The process is quite simple. Using a technical pen I covered a sheet of paper with various types of cross hatching and scribbles. Then the paper was scanned as a grayscale image. Editing the image started by using select by colour to convert the paper to transparent. To create a new brush select an area of cross hatch copy it; paste as a new image; move the selection area to select the next section of hatching; copy and paste as a new layer; repeat as needed. Save the brush with the .gih extension, a dialogue will show up allowing you to set the brush spacing and how each image repeats.
