How to Sew Buckskin.

Unless I am sewing a heavy outdoor bush moc, I dont use sinew to sew buckskin. I prefer a buckskin thong. Prepunch the holes with an awl. If you don't have a strip of iron or copper cord, use a split feather vein. You dont need the iron or feather, and can get away with just pushing the tip of the thong through each hole and synching the cord; this can be far more time consuming however as you won't always push the tip through on each try.

Make a slit with a knife - dont punch a hole with an awl - into the tip of thong. Make a U of the iron or copper cord bit as shown. Make sure the holes to be sewn are well opened with the awl. Taper the trailing end of the thong long and thin, but still reasonably  robust so you have something to grasp and draw the thing through.

A sharp, tapered nail - sized appropriate for the sew task - in a beam, with the leather pushed down onto the awl, is an easy way to make sew holes.