The string quilt that I made was on thin foundation. I don't think it made for a heavy quilt even with batting. As to dryer sheets, use the ones that have done their intended function and all the product is washed out of the fiber. They will be very soft but can easily be pressed into the shape you need. I use it for some applique pieces, too. I recently posted that those garment patterns that we don't know what to do with can be cut into appropriate pieces for paper-piecing foundations. One hint that has not been mentioned previously (that I noticed anyhow) is to alternate lights and darks as you put your strings together.