Here is the one I ordered to test. This probably does not have the power to cut metal, but I may be happy for small sanding, deburing, polishing of small parts:
20k RPM eFile 12v variable speed forward & reverse
Here is a quick video compare test to cheap rotary tool and expensive one:
Cheap rotary -vs- Proxxon noise test
The Proxxon is a nice professional expensive tool. It is also big, not something I want to use at my desk to clean and polish small jewelry sized items.