Audio-Cable DIY-Question

This goes out to the tech heads:

I want to make my own cinch-cables, and have been searching the internets for the last couple of days. the only thing i can't find for shit are those y-connector thingys to merge the two mono-cinch cables with the stereo cable.

here are a couple of pictures:

y-kabelabzweiger-0c.jpg
y-stueck-umspri-Y_.jpg

I know that the parts in the pictures are molded, but i need some to be screwed/soldered.

I don't want to go the solder-and-shrink-route, I need some kind of case around this to prevent the soldered parts from getting too much force from pulling etc.

any ideas where to find things like these? (I dpon't even know how they are called... )