Step 1: Obtain Parts
1 2"x1/2" Mending Brace
2 1"x1/2" Corner Braces
2 Hose Clamps of appropriate size for the upper shaft of your trekking pole (smaller the better)
Some Gasket Material (I found this rubbery pipe mending stuff in my closet, but I imagine an old bicycle tire inner-tube would work well)
1 3/4" long Screw
1 3/4" long Thumb Screw
2 Lock Nuts
6 or more Nylon Washers
All Screws, Nuts and Washers are 1/4"x20 thread.
Step 2: Assemble
Start by attaching the three braces as shown with the non-thumb screw, four nylon washers, and a lock nut. Don't tighten the lock nut all the way down. Leave it loose enough that you can rotate the mending brace, but tight enough that it will stay where you put it.
Next, attach the thumb screw to the other hole of the mending brace with the other lock nut and at least one washer on either side of the brace. Orient the screw so it is facing the opposite direction of the first screw, unlike in the photo (so that the first screw doesn't get in the way of the camera). Tighten similarly.