Summary

https://youtu.be/7Kw30EE4tJ0

This is a phone mount that you can customise to fit your exact phone dimensions!
It includes a 3/8 boss for mounting to anything with a 1/4 tripod screw, using one of these adapters https://www.amazon.co.uk/gp/product/B01MT77RHN/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=B01MT77RHN&linkCode=as2&tag=asmotionlab-21&linkId=c994be4289f71ce07c5f0e2d49650b6d.
Use it with ball joint heads, suction mounts (great for GPS on holiday!), gopro tube clamps on a motorcycle, vlogging sticks, magic arms, lighting stands, etc etc

The connection should be very strong as the 3/8 adapter has quite a large diameter and the thread is quite chunky.

Just dial in your phone or tablet's width, thickness, whether or not you need any side button cutouts and the wall thickness you want.

Scales all the way from small to huge. Can be used in landscape and portrail orientations - in landscape you can just use it as a desk stand.

If you customise one in landscape, make sure to increase the wall thickness (3mm+) otherwise the grip might be too loose.

I use one in my car with a suction mount, and one on my motorbike with a few gopro swivel extensions.

It's best to print it from ABS as it's more temperature resistant if you're planning on using it in the car, but PLA also works well (is what the mounts in the video are made from).

The Thingiverse Customiser preview is terrible, so it's best to download it and open it on your computer with OpenSCAD, where you can dial in your numbers.

The STL file is provided as reference - I customised it for my Xiaomi Mix 2s.

Thank you to the user 'walter' whose design inspired this one (https://www.thingiverse.com/thing:512350). Mine's geared towards mounting the phone on a rig or some sorts, but can be used as a stand too if you like.