You reminded me of an old sweatshirt I once had. A quilt block (right side to wrong of shirt) was sewn to the inside of the shirt then quilted. You have to quilt 1/4" around the block design. Turn shirt back out and carefully trim out the sections around the stitching. It gives a stained glass look. I don't have that shirt anymore but maybe someone on this board can explain it better or provide a photo.
Sorry if I confused you.