I dont know if you have ever made any custom interior parts before but there is a material called Duramix 40/40 and 40/60. Its in a double tube such as bathtub calking and it works awesome for custom fabbing plastic interior parts. Its mainly used for filling holes and blending 2 pieces into 1. Such as blending the outer trim ring of a head unit into the dash to make the factory look.
http://127515.brightwebsite.com/stor...6-oz_9505.html
So if I were you I would use the dremel idea and then If you wanted to clean it up and make it look good use something like that and then sand it down and paint it black.