I made this improvised pattern (lovely don't you think, but handy) by measuring my largest tea pot, this way it will fit over all of them. It turned out to be 16 inches wide at the bottom; 10 inches high and 7 inches at the sides before the curve. This should fit any regular size tea pot.
12 inches of the following plus any trim or accessories to add embellishments; the fun part! All seams are the standard 5/8 inch.
Lining fabric; it won't show so you can get a little crazy here.
Pre-quilted fabric (easily available) or a piece of batting. I used quilted fabric. This is a great way to use up some of those odds and ends of left over fabric. The one I used was a sample I bought when I was looking for fabric to use in the kitchen.