1/8th inch drill bit, into the plastic housing that ends up flush with the door - put the hole in at an upward angle from the lowest point you feel comfortable with, and drill nice and slow so you don't zip the drill bit into anything inside the housing. Kinda hard to explain, but if you look at the housing where it meets the body, there's an angled part that comes from the body towards the center, and then a part that's flat that has the rest of the mirror housing in the center of it. I drilled my holes so that they angled in from the top edge of the outer, angled part of the housing.I know there is a thread here about the outside mirrors dripping after washing your Jeep but I can't find it. So I have a 2012 JK, where do I drill the drain holes?