I've made several self bows of walnut, it makes a nice fast, beautiful bow if left long and wide. I seems a bit brittle, inclined to break suddenly with no warning. The lighter colored sapwood makes a much superior backing, the darker inner wood seems to hold up better in compression. Stay away from kiln dried boards of walnut, I've broken a half dozen nice straight ones on the tillering stick before getting to full draw. Try to find a whole log, or an air dried board of half light, half dark wood and it will give you the best chance of making a good, durable bow. I recommend starting out at 70" and 2" wide for a 28" draw Good luck. Kirk