This is a clip to connect 2 PTFE-Tubes with an outer diameter of 4mm. It is not necessary to thread the filament through, the coupler can be clipped into the side. There is one with a stopper to keep the tubes from slipping through, and one without. The freecad and step files are included for customization. Get freecad from https://www.freecadweb.org/.

Should be printable with all non flexible plastics (ABS, ASA, PLA, PETG).