You will need:
- A length of wire, at least 22 gauge
- something round to use as a mandrel to wind the wire around
- two chain-nose pliers, or one bent-nose and one chain-nose pliers
I’m using a step mandrel, and a scrap piece of 20-gauge round copper wire to demonstrate.
You should be able to make the ends meet flush in about 3 – 4 passes. Too much back-and-forth movement will make the jump ring brittle and misshapen.