I needed to clean corrosion from an electrical contact buried deep at the bottom of a small (~1/2" id) tube. The perfect tool for the job would be the 1/8" diameter wire brush sold by Dremel. Sadly the shaft on these brushes is too short to reach the contact.
I first considered building an extension shaft to fit the Dremel. That would mean single pointing a female thread to fit the bastard proprietary thread that Dremel uses for its collet chuck. Not an easy task and too much work for such a simple job.
The Dremel collet thread is only a tiny bit larger than 1/4" and I have the necessary tackle to cut 1/4 - 40 threads. I'll build a pin vise using 1/4" steel and the available Dremel collets. Rather than powering it with the Dremel, I'll use the Milwaukee cordless drill - less speed than the Dremel but plenty fast enough to brush corrosion from a contact.
Here is the finished "extension pin vise" and the mentioned wire brush...
By sizing it to use the Dremel collets I now have as a bonus a very slender multi-size pin vise to use as a hand tool as well as powered. In fact, I've already cleaned gunk from some delicate jewelery by chucking one of the Dremel natural bristle rotary brushes and using the thin contour to reach into tiny crevices.