These are not as good as buying real release rings that have metall teeth, but they have worked for me without any problems.

I am lazy and didn't want to order the extra parts recommended for Brandon Raineris great Over engineered Y-Splitter. But I liked the idea of having a locking mechanism on my PTFE tubes, so I designed a printable Release Ring to work with Brandons design (no o-ring required). 

Printing:

Print the model with the flat side on the build plate. I optimised it for a 0.4mm nozzle at 0.08mm layer height 100% infill in Bambulabs PLA-CF and PETG-CF filament (if you print with non CF material lower the printspeed), the print is quite brittle when it's not in the Y-splitter, so don't play around with it too much.

I noticed that printing only one of these will give a more noticeable seam that might interfere with the mechanics of the part. So I recommend printing 4 close to each other on the build plate. The extra one is in case one breaks during installation.  

Assembly:

Start with pushing the Release Ring into the Y-Splitter, then push the PTFE tube into the Release Ring, make sure the PTFE tube goes all the way in (wiggle it a little bit to get it in place), pull out the Release Ring slightly (0,5 mm) so you can push in the Locking clip from Brandons design. Its a tight fit but that PTFE tube ain't going nowhere by itself.

If you switch the PTFE tubes out a lot these might break but that depends a lot on the material you use for this print.

It ain't much but it's honest work