Thanks for all the suggestions and comments. Originally I had told my customer that I wouldn't be able to use the t-shirts for the back, but once I started cutting the t-shirts, I started questioning myself (no one else does that, right?). I've made t-shirt quilts with a light weight batting and cotton backing, and an all over pattern, and haven't had a problem stitching over the t-shirt designs, but hadn't thought about stitiching over the designs on the front and back. Not sure how my machine would handle that, and don't think I want to find out! We had talked about making 2 quilts because of the number of t-shirts she brought (2 small laundry baskets full!). She has them marked with masking tape to indicate the areas she wants in the quilt, and requested the areas be sewn together as a collage, with no sashing separating them. This should be interesting! Wish me luck! I'll try to post pictures after I complete it.