Stopper for cords and strings.This is a somewhat unsuccessful attempt because I wanted to use all printed parts so instead of a metal spring I used a plastic L-shape that has a travel of arround 5mm at the given size. With proper spring it might work better... Print parts from parts1 and parts2 files and trim L-shape to needed size. Place L-shape and inner cylinder into the outer cylinder, measure travel distance and drill holes through the outer and inner cylinder at the position where inner cylinder is as far in as it can go. Put plunger through the top and glue it to the inner cylinder. Place L-shape inside the outer cylinder, place inner cylinder in and glue the top to the outer cylinder.