Handles make great Handles!
Cut the handle off a skipole, plug, drill, and pound a file into it.
Then file the bars off one of our torture prisons without getting a blister.

Step 1: Cut the Handle Off the Ski Pole

Perhaps you recognize some of the luminaries in the background.

Step 2: Deburring

Use the skinny part of the file to scrape the burr off the inside of the pipe.
File the outer burr off.

Step 3: Plug the Handle

Find a stick that's about the right size to fit in the pipe. This one had already been shaved down at one end.

Step 4: Cut the Plug

Jam it in as far as it will go, then cut it off with enough remaining to pound it in as deep as you need it.

Step 5: When All You've Got Is a Hammer...

Sure it's too big. That's called a "Press Fit" or an "Interference Fit".
Use a big hammer to interfere with it until it's in there solidly.

Step 6: Drill the Socket

Choose a bit that's big enough that the file will go in without too much trauma, but won't fall out.
For an extra fancy socket, heat a file tang red hot and jab it into the hole to burn a nice rectangular socket.
Don't leave it in too long though, or you'll melt and burn the plastic and get sore tits from dioxin etc.
Have I mentioned that corncobs make really great file handles? They'd probably make good skipole handles also.

Step 7: Install the File

Bash the file into place, and you are ready to file in extreem comfort.
You don't want the wrist strap on there unless you're filing the bolts off a powerline tower and you don't want to drop it.
Remove the strap.
Grip your new tool and luxuriate in the rich feeling of the finest file handle ever made.
Go file the bars off one of our torture prisons without getting a blister.