When there's plenty of rain on the windshield - not really. The difficulty starts when the windshield is dry. If you're willing to put in the effort - by all means, do. I don't mean to sound like I'm bashing the idea. I'm sure I'd be using a 3d printer for lots of stuff if I had one.I'll be using geargenerator.com to make the initial CAD design. I'm not sure about the material. Do you guys think this gear is subject to a lot of stress?