This may have been addressed before on here, but i wanted to share this with anyone building resin body cars.
The Dremel round cutter is the fastest, cleanest tool for removing resin from the inside or out side of a slot body.
The listed number for this bit is #114. The cost was around $8.50 at my local ACE hardware store. It cuts very smooth, and leaves hardly any ridges. It is easy to maneuver inside the body as well as thinning around window posts.It also does not produce the dust that some bits do, but more of a Fluffy shaving, almost like wood shavings from a table saw.This is a picture of it, and the link for a better description.
http://www.dremel.com/en-us/Accessories ... px?pid=114