UPDATE(8/6/18): Uploaded new PIN/SLOT version of 90 degree mount. Have had screws break on 3-4 different 90 degree mounts and got tired of it. Decided to design a new attachment system that works with as many original parts as possible. See my other design here (https://www.thingiverse.com/thing:3037099) for new Arms and Wall Mount using same PIN/SLOT system for extra strength. Make sure to use a PLA with some flex for the PIN (PLA+) so it won't break as you flex it to fit into the slot.
UPDATE(6/1/2018): There is a strength issue with printing the screws upright, but I've found by cutting a hole in the middle adds additional strength because of the additional walls and it has held up for a while now. Added a new version of the longer one with these hollow screws.
Liked the articulating arm, but needed a way to rotate the connector 90 degrees from the previous one so I modeled this up.
Really I wanted to twist the arm braces but my modeling program is not that capable. I wanted strength so I dropped a sphere right in between the arm braces and adjusted it to look good and retain high strength.
Part of the need for this was because my remixed phone/tablet mount (seen in last photo) from [https://www.thingiverse.com/thing:2194278 ] where I added a mount brace to would only go in the rotated orientation when holding the tablet in portrait mode.
If anyone is interested in the tablet mount let me know and I'll look into making it available. That model works well for now, but needs more work before sharing.
UPDATE: Added a slightly longer one that gives 1 more tick of rotation. Haven't printed it yet, but there is no reason it shouldn't work just as good as this one.
1.2mm walls. Supports to bed only.
Took the short Arm and cut it in half(actually more like 70%) Then duplicated, spun around to overlap with original, then rotated 90 degrees so it made an arm that connected 90 degrees rotated from where it started.
Really wanted to twist the arm braces but my modeling program is not that capable. I wanted strength so I dropped a sphere right in between the arm braces and took the corners off so it more smoothly connected to the sphere.
Came out pretty good. Works well for me.