A group I belong to has a string challenge running at the moment where we are challenged to create a piece of art using string. The first technique I tried was posted on the board by Liz Gale and you soak a piece of string in ink then sandwich it between two pieces of paper. You then press down using a covered book or something and pull out the string. The first time I pulled out the string it made a solid shape. If I pulled it out again without reinking then I got the pretty striped shapes. I haven't made anything with these backgrounds yet.