If you're using paint.net, I've found a way to make scan lines! :O
First, make the pic's size 599x50 with a white background (this helps with sigs). Then make some white diagonal lines with the pencil tool, then copy / paste them evenly across the pic. Finally, with the magic wand tool, select the white and delete it. And presto, scan lines!
When you apply your scan lines, make sure you paste the scan lines on the top layer. If you don't, the blank part will override the image, resulting in frustration.
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