well ,free is way better haha.. and there is tons of it for free... pinehollowlongbows sells it ... you still have to process it even then... you could cut the tendons off road kill too.. back strap sinew I use for hafting points on arrows, sewing, building strings and such... leg tendons is what I use for backing... let dry hard pound on a flat surface with a hammerstone or hammer.. must be flat or you can cut your tendons.. and strip to small fibers.. bundle your fibers in length piles of same.. store these in a bucket with a lid too... make sure you do more than you will need .. sucks to be processing tendon during a sinew job... probably will need about 10 leg tendons or more... I'd process at least 15 so you have plenty...I start in center of bow and run sinew end to end... then lay out from there staggering tendons like bricks covering the end to end layer...... fill in any dips .. two courses is fine 3 even better ... gut