Some brushes in photoshop aready do this; you can get a nice image that looks like its flowing in nice curving wavy lines, while others will always be "upright" and when you try to do curvy lines with them they dont follow the curves but stay static, as it were.

I want to make my own brushes of a few simple lines, that I can then use to curve around on a map and show slopes of hills. I assume there is some kind of brush setting that will allow me to do this, but I cant figure out what it is.

I hope I have made myself clear. Can anyone help me out?