I recently was asked a question about attaching a leader to a fly line, and said I usually use loop-to-loop connections. Here is a quick view of how I make loops in a fly line. Using a “Tie Fast” knot tool, I make three nail knots over the doubled over fly line. The resulting loop is very strong, in fact the fly line will break before the loop lets go. You can add “Zap-A-Gap” or “Fusion” glue over the knot to smooth out the surface and let it travel through the guides easier. For more information on the “Tie fast” tool check out https://www.youtube.com/watch?v=611JWRtkjOc.
SR