Ok, kill me now. I couldn't find the URL for the article, but here is the text and the more important pictures.

How to Articles Index Make A Pop Bottle Cowl
Its easy, inexpensive and environment friendly!
By JOE BESHAR


I NEEDED TO MAKE a thin cowl, and carving one out of balsa just wasnt practical. A modeler friend suggested that I pull one out of a clear plastic soda bottle. This sounded interesting, so I found a few clear bottles in the recycling bin and developed this simple, inexpensive procedure to make a very satisfactory cowl.

1.
Make a plug of the cowl out of balsa, hardwood, plaster of Paris, etc.
2.
Use a clear plastic soda bottle into which the plug will fit as tightly as possible.
3.
Cut off the bottom of the bottle and remove the cap. Insert a long dowel into the bottom of the plug.
4.
Put the plug inside the bottle. Direct a heat gun at the bottle while you turn the assembly.
5.
The plastic has shrunk tightly against the mold plug. After it has cooled, trim the plastic and slide it off the mold.
6.
Paint the inside of the cowl with plastic-friendly paint and, if you like, add a decal or two to the outside.

You can also use this procedure to make canopies and other model accessories out of plastic bottles. Good luck and happy landings! j