The process I used to form the more complex shape of the front cover is:
1. Sculpt the shape I want by filling in the recess with modeling clay. (There are specific clays used for developing vehicle surfaces, but artists oil-based sculpting clay works fine. It's just a little stiffer to work) I smooth the clay with various scrapers made from anything handy. A short piece of aluminum scrap in this case. It worked well because I could flex it into the curves.
2. cover the area with a layer of packing tape. (Any release agent will work. I like tape rather than PVA because I can strip the tape and not contaminate the clay for the next use) Short pieces of tape on the compound curves. I have learned that it is best to put a 'perimeter' piece of tape with a curled under end to pull when removing. All subsequent pieces are layered out from there. Pull on the end and it all comes off.
3. Lay up the plys of glass dry on a piece of plastic food wrap. In this case 2 layers of 3 oz., 2 layers of 9 oz. and 2 more layers of 3 oz. I put the 3 oz. outside because it has less weave show thru that way. I pour the mixed epoxy on the glass plys, add another layer of food wrap. A small roller is used to spread the epoxy and wet out all of the glass. Too much epoxy can be rolled out of the glass into the layers of food wrap.
4. Cut the glass, food wrap sandwich to size using a rolling fabric cutter. Remove the top layer of food wrap and peel the glass/epoxy off. Lay the glass/epoxy on the mold and smooth out the bubbles.
5. Take a break ...
6. Pop the cured glass off and remove the tape and clay.