While I loved the look of my first slippers, they were made of two layers of thin cotton and not particularly warm. I had some extra fabric left over so I decided to make a new pair, adding a layer of warm & natural cotton batting to the uppers and another layer to the insoles.
I cut the pieces slightly larger (I just eyeballed it) to accomodate the extra bulk and adjusted the fit as I went along. I kept the quilting lines simple so as not to compete with the bold print.
I'm really pleased with the both the look and the added warmth. I wear them all the time and they seem to holding up to the heavy use. I would definitely make these again.