Striped Brush

[Ofnuts]

If you mean striped like this:

   

Then I have a script: http://gimp-path-tools.sourceforge.net/d...#neon-path

The script is meant to draw a gradient across a line (it actually draw several lines over each other, from wider to thinner, using samples for a gradient. So in your case:

• Create you line as paths (I assume you already do so?).
  
• Set the gradient to FG to BG (hard edge)
  
• Set the background color to the external color
  
• Set the foreground color to the inner color
  
• Invoke the script
  

If necessary you can edit the gradient (copy it first to get a "private" version, you can't edit standard gradients), to move the edge (and so select the width of the inner line).