Skin Gradients with Paint.NET v2.0Step 1:Open Paint.NET
Step 2:File -> New (Set the size to 5px x 5px)
Step 3:Zoom in on the canvas by changing the drop-down box called "Window" to "3200%".
Step 4:Use the tools called "Pencil", either by clicking on it in the menu called "Tools", or simple clicking on the "P" key on your keyboard.
Step 5:Use the colors of your choosing. Now you will have something like this:

Zoom out by changing the drop-down box where it says 3200% to 100%.
Step 6:Image -> Resize
For skins gradients - Resize the image to 768px x 30px (or what suits you the best)
For random-abstract avatars - Resize the image to 100px x 100px
Results:
By following this tutorial, you could get results such as this: