I borrowed a pair of needle-nosed pliers and small wire cutters from my dad, found a large jar of miss-matched buttons at an antiques store, and picked up artistic wire at a crafts store at $5 for 10 yards (enough to make at least 8 rings). I decided not to invest $25+ in a mandrel, and instead I used a marker that tapered a little at the end to wrap the rings for size.
I experimented with a variety of wire gauges and materials, and I found that although the 18-gauge wire she recommends looks cute and professional, slightly smaller and more pliable 20-gauge wire is easier to work with. The downside of course is that I needed to wrap the wire more times around my mandrel/marker in order to make the rings sturdy, so I used the wire up more quickly. As for the composition of the wire, brass was more pliable and held up better than colored copper. My friends loved their rings and I’m hoping to sell some of the (zillions) of extras I made at a local crafts fair.