Let’s take this step by step:
1. Get your buddy/grandpa to tie the nicest knot he can tie (for demonstration purposes, I tied my shitty, basic knot)
3. Sew up the ends that you just cut (do not sew them back together, lest you must repeat step #2).
4. Sew on the snaps. Make sure to sew them so that the ends of the tie can overlap comfortably.
It should look like this when you’re done: