I have done several string quilts. Most of them with uneven sized strings. I have used several different foundations but the one I like the best is phone book pages. However, I do take the paper off as soon as I have the block squared up. I am working on one for 2 years, as I tire of the same thing. I have 32 done but need over 60. Am going to a quilt retreat in Feb and one in April and hoping to at least finish up making the blocks then. But I so enjoy looking at all the different colors and remembering other quilts I have made. They become addictive.