Step 4: Drill the ends of the handles for the steel rods
Weld a flat washer on each steel rod. Insert the rods into the handles. Drill for a locking screw on each handle. This screw fixes the rods so they cannot shift or rotate from your setting of their angle.
Now place the spring into the countersink holes on the inner surfaces of the handles. Hold the handles together lightly and insert the nylon tie so it goes through the spring. Slip the end of the nylon tie through its own retaining hole and adjust the tension on the nylon tie for the amount of space you want between the handles when they are not being squeezed. Trim the nylon tie so the extra is removed. You may want to heat the cut end of the nylon tie with a match so it loses its sharp edge. Sometimes those can scratch and cut. (See the previous panel for the photo there.)