1. Captive rings are easy to make and with very little practice you can make these marvels in short order. The procedure is as follows:
2. Turn a bead of the size you wish for the captive ring.
3. Clear away wood on either side of the bead to make room for undercutting the bead.
4. Start the undercut from each side.
5. Before you free the ring sand the ring with as many grits of sand paper as you like.
6. Continue the undercuting.
7. Once the ring is free sand the undersides of the ring by wrapping sandpaper around the turning.
8. If possible make extra rings.
   

Tools:

I like to use "captive ring" tools. If I am making a 3/8" ring (a robust size I use for baby rattles) I will use a 1/2" captive ring tool. If I am making a delicate 1/4" captive ring (perhaps as an accent to a wine glass) I will use the 3/8" captive ring tool. The larger tool lets me focus on the tip of the tool as it undercuts the ring without concern for the trailing edge nicking the top of the ring. Captive ring tools let me make close fitting captive rings and I can usually get five 3/8" captive rings 2" across within a 3 1/2" length. There are two types of captive ring tools. Sorby, which has a separate tool for the right and left sides of the ring. The rest can be used on either side of the ring. I prefer the single tool. It is easier to use, cheaper and fewer tools to keep up with.

The scraping tip of the captive ring tool should be even with the centerline of the turning and the tool should be parallel with the floor. As a scraping tool,the tip of the tool should be pressed into the cut.

You can also use a skew or a small parting tool to undercut the bead. This usually requires more wood and ends in a looser fitting ring. Many different tools can be used to make captive rings. For tinny rings I have used dental picks. For close fitting, small captive rings I have used the corner of a razor blade.

Sanding:

It is important that the ring be sanded before it is free. The effort used to sand while the ring is still attached is minimal compared to the hand work necessary to sand a lose ring.

Wrap strips of sandpaper under the ring and use a little piece of masking tape to secure the sandpaper. With the lathe running you can make quick work of sanding the inside of the ring.

Loose rings?

What do you do with the loose ring(s) while working on the rest of the piece. The ring has very little force associated with it. So the lose spinning ring colliding with your tools is unlikely to cause any damage. If you are worried about the free ring then tape them in place. I almost always let the rings run free.

Wood:

Close grain woods work better than open grain woods. So woods like maple, pear, dogwood, apple and the like make nice captive rings. Open grain wood like oak or ash are difficult to achieve a nice finish.

Variations:

Wedding glass:

A variation of the captive ring is to interlock two rings on the stem of a wine glass. Make 1/4" or small captive rings and if the rings are very lose the effect is even better. Break one of the rings on one spot. Pull open the break and slide the other ring through. Use a drop of thin CA glue to weld the broken ring back in place. A broken ring is easier to hide the joint than a cut ring. More than a drop of CA glue will tend to stain light woods.

Baby rattle

A baby rattle has four concerns.

1. Select a wood that is safe for a baby to chew on. Maple, Pear, Cherry...
2. Make robust rings that are unlikely to break (3/8" or larger)
3. Make the rattle large enough that it isn't a choking hazard (the baby rattle should not be able to slip through a toilet tissue roll.) if you are intent on making a small rattle please drill a hole through the length.
4. Either no finish or an edible finish like mineral oil or walnut oil

Please remember that this is a child's toy not a museum piece. Sanding past 150 grit???