So I was bored in class, and decided to CAD up a slalom fin cover in solidworks. I sent the design to a 3d printing service.
Anyway, you can buy them from the link below. I don't make any profit from the sales, and if you guys want, I can add in a logo of your choosing.
http://www.shapeways.com/shops/TFitzgerald
But it does make me curious: what do you guys use to protect your fin?