
Have you ever fished a small pocket water creek, perhaps overgrown with trees or brush and thought, "My rod is too long?" Your rod is fine; your leader is too long. Have you ever fished a streamer behind a sink-tip or sinking line and considered that just breaking the last few feet off a perfectly innocent 71/2 or 9 foot leader is perhaps not the best thing to do? These are classic custom leader situations. Well designed tapered leaders simply aren't made for every application.
If you can tie a barrel (blood) knot, a double surgeon's knot and, optionally, a perfection or surgeon's loop, you can tie your own custom leaders. Many people think that knotted leaders, if properly designed for standard dry fly fishing , turn over better and cast nicer than tapered leaders.
For most types of dry fly and nymphing leaders use Maxima, Rio or other good quality stiffer monofilament for all but the last 2 or 3 sections at the tippet end. Where drag prevention is not an issue, such as for sink tip/wet fly applications, use stiff material all the way down. If you like loop-to-loop connections, put a Perfection or Double Surgeon's loop at the butt end. I like the Perfection loop; it's easier to adjust, and though weaker, I don't see how knot strength is an issue at the butt end of a leader.

The photo illustrates a little apparatus I made from scrap wood to keep leader material spools organized for production tying. The leader material protrudes through numbered holes along the bottom front edge. To keep the spools from backlashing onto the dowel, I use elastic tippet spool retainers I saved from empty Rio and similar styled tippet spools.
Below are listed some useful special leader formulas designed by Delbert Nehf, an expert nymph fisherman and Santa Cruz native. Others can be found on the Internet and for fellow obsessive-compulsives who keep back issues of fishing magazines, the following are good sources for formulas: Fly Fisherman February 2004 p.34, American Angler May/June 1998 p.31, Fly Fisherman July 1995 p. 62. I have a collection of formulas in a notebook; call or email me (423-7394) if you need some. Decimal numbers indicate thousandths of an inch diameter of leader material.
Del's Small Stream leader (6' total) .017-18", .015-14", .012"-6", .010-5", .008-4", .007-4", .006-21" . Note that even the butt section is miniatuarized, something you won't find in the few tapered 6 foot leaders available to buy.
Del's Indicator Nymphing leader (for stillwater indicator nymphing, such as is done at Butt and Crowley lakes) .017-26", .015-16", .012-12", .010-6", .008-6", .007-12", .006-30 inches for a 9 foot leader or 48" for a 10 foot 6 inch leader. This formula, as opposed to others I've tried, is actually castable.
This formula is from Orvis, and is for keeping flies down behind sinking and sink-tip lines: For 1X or 2X tippet: .021-18", .017"-15", .013-12", .011-9" .010(for 1X)-18" or .009(for2X) same length. For 3X, 4X or 5X tippet: .019-18", .015-15", .011-12", .009-9", then tippet of 18" in .008 diameter for 3X, .007 for 4X and .006 for 5X. The whole leader to be of Maxima, Rio or other good quality stiff material.
May your lines be not only tight, but harmoniously castable!