A few more sources for smaller files, diamond files, and handles.

Someone sent me a link to a file handle on the Gesswein that appears to have a collet nut so should tighten nicely around the smooth shanks of the short diamond files made for the reciprocating tools:
Needle File Handle

 

I buy a lot of stuff from Plastic Process Equipment, here are their offerings for both needle files and diamond files, note they also have a clamp-on handle for two different size round shanks:
Plastic Process Equipment, Inc.

 

I don't know if that link will go directly to the page, but the files start on page 296.

Here is the small file handle I really like; PFERD #16174, available from multiple sources, but here's one with a pic:
http://www.toolfetch.com/pferd-16174-quick-mount-file-handle-sh-220-for-needle-diamond-and-small-files.html

Dennis Storzek