I followed the basic methodology seen here, Mark's Daily Apple. With a few changes, of course. I used all of the fat that I trimmed off the beef, not just the back and kidney fat. A lot of it was thin and stringy strips. I cut the larger pieces up, but left the thin bits. I never shredded it. I didn't cut the bits of meat off either. I just spend two days trimming all of the excess fat off my beef, I wasn't about to spend another two days trimming the bits of meat off my fat. I did the oven method, leaving the roasting pan of fat in the oven at 200°F overnight. There was a lot of fat, and it took a long time to render.
In the morning, I drained off the liquid fat.
Then added more trimmings to the roasting pot, and put it back in the oven.Now just to wait for it to cool and harden.
I left some headroom, as I was considering freezing it. Freezer space is at a premium though, with 5 turkeys and all of those roosters left to butcher. I'll probably just store it in the cold room instead.