Xiaomi Yi flex holder 20 and 30 degree

Inspired by the gopro mount by questpact, which in turn is probably highly inspired by the mounts from http://creativedex.com, I made this variant for the Xiaomi Yi. There's 20 degree and 30 degree variants, but I only tested the 20deg, hopefully made no errors on the 30deg. Comments appreciated.

Some people are complaining about scale of my models in their slicers other than Cura that I am using. Blender STL export doesn't really have many options other than ASCII and 'use scene unit'. the s