I did the same as Cowlitzfisherman...cutting several 4" X 1" X 2" (approx) pieces of styrofoam out of the packing of an appliance, and they work superb. (and free too...all you want for the asking.)

Rather than cut the slots, I just lay the end with the barrel swivel down and wrap gently, but snugly over it, securing that "band" with the hook set deep in the stryofoam. I run 5 leaders to a piece of foam. (Cutting the slots sounds like a better way...gotta try it.)

They are carried in a large pocket of the vest, never once has one come out of the styrofoam. Only issue I have with it is you have to straighten any slight kinks from the mono leader, but that takes only a second.

I also pre-tie jigs/leaders, again using the barrel swivels at the top, so color changes can be done in a snap. The barrel swivels also save having stiff from the cold fingers trying to tie knots. The only time a re-tie is needed streamside is if I hang-up badly and break off the snap swivel.

My 2¢ worth..

Mike