Using fibreglass was something I'd done previously on small repairs and I knew how versatile it could be with more practice. With that in mind, I decided to make something that would test all the processes in small-scale.
I wanted to make something that I'd use but could also potentially be sold, I also wanted to stay away from things like car body panels which admittedly would have been simpler, but I wasn't confident enough of my ability yet and had visions of them breaking and flying off. With all that in mind, I settled on making a speaker box that fitted around the contours of my e36 boot.
First step was to make the plug; this was only needed for the shape and didn't need to be particularly strong or function correctly. To get a mould of the boot, lots of masking tape was used. I also wanted to try a trick I'd seen on TV where felt is stretched over an item and resin applied to hold the shape.
Although this was only to learn about fibreglass, I needed to brush up on my speaker knowledge with regards to volume required for certain size speakers. To do this, I filled the plug with water to measure the volume with the intention of reducing, if required, with packing material. As it turned out, it was pretty much the perfect volume for a 12" sub that it was designed for. As they say; if it looks right, it is right. With the plug test fitted, it needed to be extremely smooth in order to make a mould. I therefore painted it, waxed it (to aid the release) and made a two piece mould.
Despite using both wax and mould release (the blue substance you can see that needs to be sprayed on in about ~15x light coats...) I underestimated how hard it would be to remove the plug from the mould and damaged it in the process; the combination of hot water and prying with trim tools damaged the filled/painted surface of the plug. However, the mould was still good! So I decided to make a 'master' in fibreglass and then re-make one half of the mould.
With a nice sturdy, gelcoat finished master, I made the top part of the mould again in 2 pieces to make it easier to remove in future. To do this, you can use plasticine to make 'walls' where needed and also locating features if you're a bit OCD...which I am. I also drilled holes so the 3x pieces could be bolted together.
So now I'd figured out how to use fibreglass and learned several things the hard way, I had a part I could test and sell. After trying several carpet samples, I found one that matched the e36 boot carpet almost perfectly:
