Connects ball and socket chains to 20-series t-slotted aluminum extrusion. My delta printer has t-slots, and this connector allows small or temporary items to connect to the frame of the printer. It's intended to fit 20-series t-slots that have a 6mm external slot that opens inside to 12mm. I had to slightly modify dimensions to fit well with my printer, so it's possible some scaling would be needed on another printer. The OpenScad file is attached for additional changes.This was printed at 0.2mm layer PLA. It was printed with the t-slot foot on the bed with support for the center disk. I wouldn't expect it to work well without support.