You may wish, if you are comfortable with monofilament, to use a
very fine break strength, like 1-pound. Fly fishermen who make
their own leaders, especially for finicky trout, use these fine
diameters. A place like Orvis, Bass Pro Shops, or other fishing
tackle emporia could help you.
There you have it, another hopefully-karma-boosting stitch of
altruism from an ultimately self-interested supplier, Dan Woodard
at Indian Jewelers Supply Co.