The back wall of the Safari Cab is closer to vertical than the back of the factory hardtop, but for aesthetics I angled the rear wall 1" forward above the belt line.
I taught myself moldmaking and fiberglass by reading books. I believe that if someone has some DIY experience and can follow a recipe in the kitchen to bake something, then they can certainly succeed at fiberglass.
The very first thing I'd recommend is reading a book on fiberglass. This is a good one: https://www.amazon.com/dp/1557884986/?tag=wranglerorg-20
Your local library may have some books on fiberglass in the boat section. Depending on the library, these books could be from the 60's or 70's but everything in them will still apply to what you'd be doing in your home garage, and the older books won't cover newer techniques or materials that you probably wouldn't be using anyway, so older books are fine. I've got several older books here and the information in them is perfect for a first-timer - they don't cover newer materials and techniques that might confuse someone, they're just the basics, which is all that's needed.
After learning from books, I did a few very small test projects to learn the techniques and once I was happy with those results I went on to my first "real project", the TJ/LJ Safari Cab hardtop. That was really my first from-scratch complicated design where parts had to not only fit on the Jeep but fit together with each other in a modular way. The project was successful - almost 10 years later, my home-made Safari Cab is still in daily use on my LJ, and Gr8Tops licensed the design from me and they've had it in production for some years now. My home-made parts just out of the molds:
Molding the parts is the easy part, like I said if you can bake a cake you can do fiberglass layup. You need to have a good design first - the fiberglass parts need to be well planned so they will fit together as intended, work properly and be strong enough. Then you need to build correct molds. Accuracy is important - the final parts will be an exact replica of the mold, so if the molds aren't built accurately to the design, the parts won't work as expected. And when all that's done, the easy part happens - the actual molding of the parts. It's not really all that hard to to the mold release, gelcoat and layup steps to get a quality part.
Happy to answer any questions you might have on design issues, adapting something like this to a Safari Cab hardtop, mold making, or fiberglass layup.
