I made it at TechShop, with their state of the art equipment. You can think of TechShop like a fitness club, but with tools and equipment instead of exercise equipment. It is sort of like a Kinko's for makers, or a Xerox PARC for the rest of us.
Their website is techShop.ws
Step 1: Sizing
Here I'm using SeaSprae, a light weight polyester fabric. It shows marks and stitches well, but it not the fabric I'd use to build a burgee cover. Normally, I'd use Sunbrella, but it's harder to photograph.
Ordinarily, I would not make all these marks on the material. It works well here to show what I'm doing, as well as to show the inside vs the outside. All marks here on the on the inside.
Step 2: A bit of math gives us cut sizes
The finished diameter is 3", times 3.14 = 9 1/2", plus a 1/2" seam allowance on each edge = 9 1/2 + 1/2 + 1/2 = 10 1/2" wide.
Step 5: Fold the bottom edge
Fold the bottom edge 1/2" "inside to inside" and staple or pin into place. Creasing the fold will make things a bit easier to sew, but I didn't crease it.