For those who want their polymer clay beads (or other small items) sanded and/or buffed, but can't or don't wish to do it piece by piece, by hand, a rock tumbler may be just the thing.
Though nothing can equal the fine finish achieved through careful hand sanding and buffing, rock tumblers are useful tools for those who have many small beads that are too tedious to sand and polish by hand. Tumbling can also be a lifesaver for those with physical difficulties, such as carpal tunnel syndrome, which might otherwise make them unable to sand and buff their polymer clay beads.
As helpful as tumblers are for some people, it is well worth researching them and common procedures for their use before running out to buy one. As with any tool, it has its benefits and drawbacks. For instance, sanding or buffing with tumblers requires a little more preparation than sanding and buffing by hand. After finding the correct grits of sandpaper, you'll need to glue sheets together (with waterproof glue), then cut them into chips. For buffing, you'll need to cut soft, white denim into small pieces.
Another drawback of tumbling is the time it takes. Some people don't mind the time, since they can leave the tumbler running "in the background" while they're at work or play, but it does take a while. Those who use the vibratory tumblers say you need a minimum of 6 hours per grit. Rotary tumblers take as long, or longer. If you're going through four (or more) grits of sandpaper, plus a round for buffing, this can add up to days of tumbling, per batch of beads.
It is also important to note that tumble-sanding works best when your beads are already relatively smooth and regularly shaped. You should know, too, that you won't achieve the same high shine with tumbler-buffing that you get from buffing with a buffing wheel. However, after tumble-buffing, it should be quick and easy to reach that high gloss with a little work with and electric buffer, if that's the look you want.