How do I make these tweeter pods?

I am looking to make my own tweeter pods. I know my locations are not the best for some but I like the looks. But I am not sure how to fabricate them. I have read enough on how to work with fiberglass. But how would I make this.... I have MB quart QSD's 6.5 I think the tweeters are 1". I am thinking that I have to use the moun that the tweeter fits in, surface mount. I was thinking I could mount this to my stock sail panel cover. but then what? Do I use plaster paris (sp?) and build up and sand until I have the shape I want, then cover it with fiberglass? The other tricky area is how to get the fiberglass to look nice along the edges of the tweeter mount. Then I also want to mount the rear tweeter in the holes where the rear seat belts are, on the top rear quarters. I was thinking something that looks like a autometer pillar pod for gauges. I guess my reall question is how to I make a mold or what to I use as the sub structure, and then how do I roll the fiberglass to meet with the tweeter grills.

You will get a better response if you post this in the Fiberglass forum https://www.the12volt.com/installbay/forum_topics.asp?fid=16