The whole idea is to cut smooth curves and just sew them together. You don't worry about any seam allowance. I started with a 3-1/2" square and cut a curve in the one side. I cut the next piece matching the curve and sewed them together. I used a little less than 1/4" seam to sew them together.
As you can see it looks like it is going to be a problem...
But it isn't...a little squirt of water and a hot iron and ...
The block is remarkably flat. It is about 12" 'square'!
I do have a few tips. Each piece I added was made extra wide until I got a feel for it. Each side you'll end up cutting a curve out of it so you don't want to shortchange yourself. You don't use any pins for this technique. When you start sewing use your needle down position. You'll be stopping a bit until you get a feel for your hand motion. My left hand held the underneath fabric and the right hand held onto the top fabric. It is a bit of a juggling act to line up the top and bottom but it doesn't take long to get a feel for it.
My mind is swirling with the possibilities, both simple and VERY complicated.
I would have missed out on an amazing technique. Thank you Blog!
And thank you Ricky Tims!