Ive bought one of those furled leaders 
over at Highlanders site. . They look mighty fine.
They are hand-woven leaders & represent a vast improvement over nylon & braided types. For top water & sub surface fly fishing they are without equal.
Construction…..Take over 90ft of premium nylon, twist & counter twist to form what is not unlike a thin rope & you will be getting near the answer.
Form length & taper to suit fly line size. Incorporate loop to loop connections. Add a tippet to suit & we are nearly there
Finally add 250 years of history & maybe, just maybe we might have the answer. Newton & Walton, they knew the answers, nylon has now replaced the twisted horse hair & silk of their time, but the principal remain the same.
Sounds good. Now all I have to do is keep myself from getting caught up in some jaggy bushes (or a rusty old car) and the coming season is looking good.