I'm looking to make a eg air duct out of fiberglass but don't really know where to start... I was wondering if someone could give me a little tutorial or guidence to making them... I know it can't be that hard... I fiberglassed before but don't know what to start for this project... heres a pic for some reference.

 

the easiest thing would be to mold it :D

I personally would built it out of wood or cardboard to mold off of...

 

the best way i have found to make stuff with curves and stuff is use fleece from the local fabric store.you then just but fiberglass resin on it . let me know if you need more help

 

I like your idea... that would be the simplest way I think... no messing with molds or plugs at all.
But how do you mean the pipe part?

 

was going to get started today but its freaking snowing outside right now But the way I was going to do is was just fill the section with foam, then pop the foam out and add the section for the tube one there, then fix my flange for the lip side. Now what type of foam could I get for this project and where is the best places to look in the states?