I made this adapter to go out the back of my AirSense 10 CPAP machine sideways rather than straight out. I also used a hose clip to bring it around the side of the machine for front exit: http://www.thingiverse.com/thing:3759686. The right-angle exit makes it much easier to place the CPAP machine in limited space.
This comes in two parts, the elbow and the coupler. I made the elbow out of standard PLA, and it's from the Tinkercad parametric elbow tube shape, customized for the CPAP 22mm OD to fit standard hoses. I put a standard-ish 15mm ID on the elbow.
The coupler I made out of TPU to make it a little more stretchy for a good and adaptive fit. You can make it out of PLA but you may have to chamfer the inside to fit the other parts.
Hatchbox PLA + TPU
I set standard brim and supports in CURA. It's a pain to remove but that's life.
I used a 220 deg. nozzle temp and a 60 deg plate temp on the standard Ender 3 polymer sheet bed. These are my standard PLA settings.
I also used a 10% infill overlap percentage to get good internal adhesion.
Oh, yeah, and if you use TPU make sure to set your speed down. I used 30mm/sec on the TPU, with 230 degree nozzle temp and 40 deg plate temp.
The supports inside and outside require a fair bit of work to remove. Be patient and careful. I don't know any better way to print an elbow. Let me know if anyone has suggestions.