You can use duck breast and legs, or really any meat. I used breast and legs from 3 ducks.
Coat duck parts in kosher salt and garlic (powder, salt, minced - doesn't matter). Place in pan in one layer, close to each other. Cover and place in fridge overnight to a few days.
Rinse meat, soak in cold water for a while, pat dry.
Place in single layer in crock pot. Add olive oil to cover meat. Cook on low until falling off bone. 10 hours in my crock pot. Remove meat to smaller container, Cover with oil. Cover and store in fridge. Supposedly good for weeks.
Strain remainder of oil and store in fridge to reuse or cook with.