If you tie your own flies, you’ve been in that situation before. You’re just finishing up a great fly, getting ready for tomorrow’s trip, and you can’t find your whip finish tool. Or, if you’re one to take your tying kit with you on trips, it’s the one tool you left at home.
Regardless, it pays to know how to whip finish by hand, which is why this piece from Grant Michaels over at Fly Lords is worth your time to read through. He has a video as well, and you can look through both here.