To make the pouch easier to tie off, I made a lining of roe deer buckskin. The skin is cut against a board. Keep in mind that it is easier to cut reliably in a pushing motion rather than pulling.
The sinew thread is single ply strands from reindeer backstrap sinew. It is twisted like this to keep it together. For longer, stronger threads I'd use two ply threads, but for this project that wasn't needed.
The small tear down in the bottom is sewn tight with an antler needle. For this I used a simple overhand stitch. For the rest I used running, double stitches.
On the top of the lining I sewed in a short braided cord of elm bark to tie off the opening of the pouch. The knot here is excellent for tying off the end of a seam.
The finished result: A tinder pouch.