I use a Nexus 5X to interface with Octoprint, so I needed a good way to keep the phone handy at the printer. This bracket mounts to the frame of a Monoprice Maker Select V2, or any other printer with four 3mm bolts spaced 30mm apart, and securely holds the phone. The bracket gives you access to the power button and charging port, but doesn't give access to the volume controls (I didn't need them). If you're using the Maker Select, you'll need four 12mm long 3mm x 0.5mm cap screws and a hex wrench to install this (the original bolts aren't long enough).
If you're looking for a bracket for the Nexus 5X that's freestanding instead of mounting to the printer frame, try this: https://www.thingiverse.com/thing:3540809
Note: My printer has z-braces installed, but they're not required to mount this bracket.
For the most efficient print, orient the model right side up, with the charging port for the phone facing the build plate. I suggest using a brim to keep all the parts steady, and supports for overhangs over 60 deg.