I'd like to drill some holes in my back bumper. What's the best way to drill a hole from the backside (which is un-painted) without chipping the paint on the outside?

Should I use a small bit first then gradually make it bigger? Should I use masking tape on the painted side? I just don't know what to do.

By the way, I'd like to drill about 60 1/8" holes. (All the post-mod picks will explain why.) Advice?

masking tape, prob better to drill a pilot hole from the outside then go slowly from the back