Bead Chain connector

thingiverse

To join ends of a bead chain or fix a broken one, these small parts are often used. They're frequently found in roller blinds and similar applications. The scad file contains several parameters that can be adjusted, such as the ball diameter and the wall thickness. The top part is simply pressed into place, allowing for some adjustment to accommodate varying tolerances. In this particular model, a 4.5mm diameter and 1.5mm wall strength have been specified, along with a tolerance of 0.2mm.