Turn crockpot on low. If you wish to melt faster, then grind leaf fat with meat grinder. Otherwise 1"-2" chunks works well
Fill crockpot with leaf fat, cover, and let melt. Check between 6-8 hours or 2-3 hours if you grind it and dip out with ladle.
Pour through cheese cloth (as filter) into glass container, let cool and use. Shelf life is 6 months in refrigerator and 1 year in freezer.