I finished the drum bag prototype for the bellydance studio today. I'd been meaning to do it but then wanted to sew only for me. Over the last few weeks I've had some ideas in my head and I was finally able to get it done. It's made of black quilted cotton broadcloth with piping and straps.
The bag is smaller at the bottom than the top, to accommodate the shape of the drum. For my first pattern, I just took the extra off at one end of each side of a rectangle to form a trapezoid... but then I realized that this wouldn't work because the seams wouldn't meet at right angles. The way to draft the pattern is to start with a big rectangle and then fold small, evenly-spaced darts out of one side to make an arch-shaped piece. This was perfect.
Then I realized that I'd included too much ease and had to trim it down a bit. Fortunately that wasn't too hard. I'm quite pleased with the bag, overall; I've serged and top-stitched my seams for strength and attractiveness. And now that I know how to make the bag, it would only take a couple of hours at most to make another one.
Hopefully it will be the right size and design and the studio will like them. If I were to sell ones like this myself, I'd probably sell it for $25. If the studio wants to sell them, I'll sell them for less (bulk orders get a discount, of course :)