This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
From: firstname.lastname@example.org (Paul Hamilton)
I put on a clear coat of dope or Krylon, sand with #600 wet-or-dry
sandpaper, and then buff with "Rotten Stone" or similar rubbing compound.
This is a fine abrasive that on mixes with water. I have used toothpaste
or silver polish as a substitute for rubbing compound when there has been
no hardware store around.