FG spoiler build

wondering how to build a spoiler / visor for my car out of FG. Here is some  pictures of what I want to do.  Is if hard? and would I be able to do it?. I have worked with fiberglass before and I am pretty good with it but I need to figure out how to get the shape of the spoiler and what would be the best way to do it. Any ideas I would be most thankfull

All good answers there Nicholas.  If you use the sheet foam method, use the blue kind that is closer to the thickness you want.

Cut a template out of the upper portion of the window so you can fabricate a contact section, which is the actual bonding surface to the window.  Lay the template on the foam sheet, trace it, cut the foam out so you have a "plug" that is the U-shape (that is if its the same shape of the car in the picture).  Then make a template for the shape of the upper visor section.  Lay, trace, cut this part out.  Glue/tape the foam parts together the way you intend them to be, and test-fit.  Sand/grind/contour the rough edges or sides down to the desired shape.  Cover the surfaces with foil.  Apply resin, then glass sheet or mat to the top-most section and saturate with more resin, roll it out and let cure.  Turn the part over as if your looking at the mounting surface.  Apply resin to the mating surface, then FG mat (make the mat of this part overlap the other section so that there is a bond of the two.  Lay more resin/FG mat as required to your desired thickness (you can always sand it down a little).  I wouldnt do more than 3 layers since it doesnt support anything other than resist wind flex.  After the part is fully cured, pour laquer thinner, carb or brake cleaner in it to melt the foam away.  Finish the part out with body filler, putty cote, ect...paint it.....attach it with 3M double sided tape....

Ive only fabricated 4 of these for 4 different cars.  What car are you fabricating this for?

What I did was taped off the top as neatly as possible then layed glass over that.I have cut out the section of the spoiler that will contact the window that is shaped like a U that. i have pictures at http: www.cardomain.com/ride/2123181/3        .My question is what do I do next. The part left over from what I cut I am using as the plug that will give the gap between the window and spoiler. I took the  plug and sprayed foam on it and I will  sand to make the negitive. there is a diagram included to show what I have done so far. If there is a better way or I am doing it wrong please let me know.