Now that you have several pieces of fat, trim them so there is little to no meat attached to it. The cleaner, the better, as it will otherwise affect flavor. Chop them in cubes, place in a pan in the oven, and set the oven to 100-120° C/ 210° – 250° F, not higher. You want it high enough for the fat to melt, but avoid it burning, as it will ruin the taste.
So how long does it take? I usually render fat at 250° F for 3 hours. You can tell it’s done when the cubes of fat start to brown a little on the surface.
When it’s done you strain the fat through a strainer, with some paper in it. Coffee filters are usually too dense, so use a regular paper towel. Place the fat in the fridge, and use later for cooking!