You can make a good trap ring for staking using the same method. Make the jig out of 5/8ths inch smooth rod. Use 1/4 inch annealed rod for the ring. Stick one end between the rods and bend one end of the loop. Pull it off the jig, and put the loop around the outside of one leg of the jig and bend the rest of the way around the other leg. Cut it off to the right length, put your chain on, tap the ring closed and weld or braze the ends together. I start with a 5 - 10 foot length of 1/4" rod and bend a ring, cut it off and bend more until the length is used up. No guessing as to how much you need for each ring, and you've got the leverage to bend them easily.
Smooth rod works better for the swivel jig as well, makes it easier to get things off after they are bent.