Pictures you ask? I just happen to have some. I have some packages of sample batting that I decided to use. Three of them stitched together fit just fine. I butted the edges together and zigzag stitched them.
You may have a strip wide enough left over from a quilt being quilted. This would be perfect and eliminate the pieces being zigzaged together. All you would have to do is stitch the edges.
Slip in the ruler and WA-AL, I mean LA!
Works like a charm--a charm square, that is!