Original design by FlorentBonnefoi: https://www.thingiverse.com/thing:178047
I moved the hole where phone camera should be placed to the center of the adapter so that you can use phones where the camera is on the center of the backside. I also decreased the cylinder diameter and made the piece that holds the phone simpler and wider so that my Nexus 5X fits. Notice that in my purpose (Karl Suss PSM6 probestation microscope) the phone is placed horizontally so this simpler piece is enough to keep the phone still. If the adapter is tilted, this solution might not be strong enough to keep the phone still. For assembly you need 2xM3 nuts and bolts.