With glass laminated bows, if the stack and tapers are just so the tillering is sorta built in.
With wood bows wood is removed and the bow exercised,to teach it to bend.
With glass bows once,strung you,measure at each fade to see how they compare. Usually I want the bottom limb a little,stronger by about 1/8 inch. This can be,adjusted by sanding the edges of the limbs and also the face of the glass.
Most often it will,come out close.