Backing for Polka Dots Whirlygiggle

For the Polka Dot Whirlygiggle, I decided to pull put whatever dotted flannel I had around and see what I could come up with. So I went from this -




to this, note the pen and paper for math -



with some precise-ish cutting to this -



Which has just the right amount of overage to fit on the frame. Mostly. Sort of.