I made one file handle and used 3/4 copper pipe for the ferrule.
But now it looks too nice to throw in the toolbox but I did anyway

I got it pretty close on the lathe but to get the final fit I used
180 sandpaper so the ferrule just barely fit.

Drilled the first hole to match the small end of the file then
drilled part way with a bit that was a little smaller than
the wide end.

Held the file in one hand and beat on the other with my carving
mallet. This was a small flat metal file. 1/2" wide and 10" or so

Sprayed it with a few coats of lacquer and all's well

I stood out in the sun and sprayed all 3 coats quickly
rotating the handle for quick drying and no running.