I`ve made a lot of bows thru the years for little bitty kids out of 1/2" PVC by cutting a notch in the ends,tying a knot in the ends of a piece of string and sliding the string in the slots. I usually used a piece 3 to 4' long. I think if I were you I would start with a piece about 6' long. You can always cut it shorter,but its hard to add back on.