By unexpected popular request I'm uploading the parts I created for installing a modern LCD head unit in my Land Rover Discovery 2.
This tray fits in the centre cubby box and is specifically designed to fit an iPhone X in a case, with this style of magnetic connector:
The connector is held solidly in place and the phone is held in place by the magnetic connector. I've had no issues with the phone moving and becoming disconnected.
It consists of four parts as my printer isn't large enough to print everything at once, but it would be much stronger as a single part. It could also be CNC machined if you have the equipment, I've always thought an anodised aluminium version would be nice.
I used a DIY flocking kit to cover mine, it was my first attempt and it certainly isn't perfect but it's good enough for now. A patch of thin felt where the phone sits might be better, it just needs to stop the phone from sliding around.
There is room for improvement, feel free to tweak and please let me see the results. This is quite a snug fit in the cubby box of a Discovery 2 and presumably will also fit a 1995-onwards Discovery 1 so would be a good basis for your own.
I created a video on this and the other parts created to allow me to fit an Alpine iLX-702D to my Disco 2.