I have been hitting thrift shops for the past several weeks, grabbing all the 100% wool sweaters I could find that were of a "winter palette". Soft blues, soft pinks, grays, off-whites. I even scored some great cheap cashmere. It was nice coming across so many vintage sweaters with "made in the u.s.a." and union labels. Quite a few sweaters that are out of fashion, and/or with stains and holes will be able to repurpose themselves in my project.
I have been felting. A lot. Just a note: you CAN felt in a front-load washer. There is a myth it cannot be done. It can.
Only 2 sweaters of the bunch would not felt. I'm not sure how the manufacturers do it, but they can treat wool so it does not felt. There is no way that I know of to be able to tell if the sweater has been made with this process, but since I only ran into this problem twice out of probably what - 40 sweaters - it's not a big deal.
My project is going to involve cutting the sweaters into squares, zigzag stitching them together side by side (not 'right sides together' or overlapping. there will be no seams). Then I'll probably put a backing like a regular quilt. No batting needed.
We'll see how it goes. I'm kinda winging it.