I recently came upon this. Ingenious. However, I took some fabric out and just laid the charms on top of the ten inch.
You need to use a charm square that you cannot see through or line the charm square. Otherwise, the bottom fabric shows through. I do absolutely plan on doing something with it. I bought a layer cake Lady Mary collection, and I think it would make a fabulous quilt with this technique. I just need to get a heavy enough charm square fabric for the center. I had wanted to use the same charm square fabric for the entire quilt. I'll have to start experimenting with my stash.