Pliers handle repair

Many pliers have sheathed handles, which hurt the hand, tend to slip back, and at last being lost. However, the pliers can be sharpened, derusted and oiled, and work very well. Take out all your pliers, and upgrade them with these handles to put them back into service.
If you want maximum clamp opening travel, slight constant opening force, and mostly avoid buckling of the spring, the spring selection is difficult.
With lots of tests I advise approaching the following parameters Øwire 0.7 outer diameter 9 mm (redrill the handles) And the approximate total need length is 60mm. If you have nothing at your home, there is good low cost seller on ebay with spring parameter configurator.
It is better to print in PLA to facilitate gluing the handle, choose a polyurethane (PU) glue-putty. Otherwise in abs you have to alter strongly the internal surface to allow adhesion and prevent it from demolding. Once dry, sand the handles (belt sander).
If the pliers do not fit into the handles, heat