A part cleaning tumbler can help clean and/or polish metal parts. A tumbler involves a base unit that vibrates or shakes a tumbler bowl attached to the top of the base unit. Tumbler media loaded inside the bowl is circulated around the tumbler bowl by the action of the base unit. A lid fastened over the tumbler bowl keeps the media in the bowl. Metal parts that are small enough to be tumbled around in the bowl are put in with the media and the unit is then allowed to operate, typically for hours or days, to clean or polish the metal parts.
A wide variety of tumblers are now available through various suppliers. Sporting goods businesses that sell ammunition shell reloading equipment are a good place to shop for tumblers as the tumblers are used to clean spent ammunition shells during the reloading process. Tumblers can also be found in larger automotive supplier and hardware/tool businesses.
I first started with crushed corn cob husk and walnut shell medias. I found the corn cob husk media to be useful for only polishing clean parts. The walnut shell media is a bit more abrasive and was better [for me] for the general polishing of old parts. I also use stainless steel shot (available from larger jewlery supply businesses) mixed in with walnut shell media for better cleaning of parts. Another variation that I have tried is to mix off the shelf metal polish with the walnut shell and stainless steel shot mix. The idea, again, is to experiment first with different medias and mixtures to see what works best for your needs. Since I have started using a tumbler, many additional media types (including ceramic ones) have been introduced on the market and you can really get creative by experimenting with different types of media. Some people even use certain brands of cat litter as media.