pat the fish bladders usually come packaged.. most look like and are the size of large chiccarones or large pork rinds ,,sometimes the uncooked ones are very hard to find here in the usa.. 2 large bladders will be enogh to size the bow back several times,,as far as the amount for the sinew,,for me it depends on several factors..the amount of sinew,number of courses, and the coarseness of the sinew,and whether its back or leg tendons.. james