Making fairings is a pretty complex and involved process but it's worth it in the end, there are a few ways to do it, but one of the easiest and by far cost effective way to do it is the same way architects do.
What you will need is some modelling foam known as Aurora, there is a foam supplier in Rydalmere that will cut the foam as thin and as large as you need and it's pretty cheap.
Aurora is the foam you see in floral arrangements, you know the stuff, the green hard foam they press the stems into... this foam has high properties that you will find awesome when working with it... This foam is also used by bodykit manufacturers when developing on off kits or prototype kits.
The foam can be shaped by using your fingernails and fingers, you don't need any real complex tools to shape it, i use my hands, a sharp knife (to cut away large sections or detail sections i want the fibreglass to slip into.
Lay the foam section over your frame and you can at this point use bolts to screw into your frame to keep it there while you shape the part, you can also glue other sections to the foam using a 2part glue or strong as nails type glue, but remember being foam it WILL soak up the glue to use enough to glue it, but also take into account it will soak into the foam...
When you have the shape and style you want, take off the proto part and lay fibreglass over it (taking into account the thickness you are going to have make sure you have compensated enough by taking enough foam off, dont just shape the foam thinking that will do, you will have to shave off around 10mm for the fibreglass)...
When you have fibreglassed the part then rip away the foam from behind and sand the back down with 80 grit paper,,, You should be now have a fairing design that no one else will have and it's totally a one-off part!
Hope that helps some ... and gives you an idea...
