Dremel Speed Chuck
This is a very cool device that screws onto your Dremel and saves you lots of time switching collets to secure your various Dremel shank-sizes coin cleaning tools.
Trust me, this adjunct, added to your Dremel is a true blessing. You can toss away your collects with a sneer, never needing them again!
Word to the wise: If you are using your Dremel tools under running water, as I always advise, you will need to "oil" this tool every month or so, just to be sure that it doesn't rust up.