I used a can of this (the small red dip can):
Amazon.com: Performix 11601-06 14.5OZ Red Plasti Dip Multipurpose Rubber Coating: Home Improvement. Your local hardware store probably carries it, and it holds up fine. I just used some string to hang it in the air (by the threads) to dry and did two coats (dip, hang dry, dip again, hang dry again). Here's a pic of it on the car, although it's partly hidden in shadows:
