Walnut is actually pretty well balanced as a self bow. Providing that you have a flat back an d a flat belly. The only way that I would trap it is with a hard backing such as white oak, hickory or something similar to those. On a pyramid style stiff handle bow, I usually go with about 2" wide at the fades for a few inches and straight taper to the tips. Make sure the working limb is draw length + 1" and take your time. If you go with a soft backing such as rawhide, linen, silk or whatever, the crown will no longer be a concern. The hardest thing for me with walnut is chasing sapwood rings. They are just plain hard to see. If you have to do that, have good lighting and a wet rag handy. If you lose sight of the ring, just wipe it with the wet rag and the grain will show up better. Josh