Lets say i have a kit that has a simple bubble canopy. like a scale glider for example. I know about how to take a 2 liter pop bottle for material, make a frame and pull form it, but making the plug is another story.
Instead of going through the hassle of taking a block of foam, or carving one out of a prime piece of balsa to make a plug, wouldnt i be able to turn the original upside down and pour in plaster of paris, let it harden and use that as my pull form? Seems having a canopy to start with to duplicate one is half the battle, but how to i get from point A to B with it?

I have read on RCU where plaster of paris works well for this. Do a search, and learn more about it, then go for it!

I did a search on "canopy" and there were no topics started on this. Still looking for ideas.

Try this one http://www.rcuniverse.com/forum/m_2076969/tm.htm

Oh, I forgot to mention, that thread is about using plaster of paris after starting with a sculpted clay plug.

But to answer your question, yes, filling a canopy with plaster is a common method of making a plug to duplicate the canopy. Be sure to support the canopy so the weight of the plaster doesn't spread the sides while it's curing.

To duplicate http://www.rcuniverse.com/forum/m_4107817/tm.htm