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You study the instructions about crossbow cable-backing. By adding and tightening a cable made of animal sinew or leather along the limbs, it is possible to increase the draw strength without risking breakage or fracture of the wood. This process begins by securing the crossbow with clamps to help unstring and secure it. Then some shaping and carving grooves for the cable to sit will be necessary. After a time the leather strips can be assembled onto the bow, followed by some touchup shaping. To finish, more stain must be applied to the crossbow.

push cross with clamp
You have no idea how to craft crossbow cable-backing from this.