I did this for mine OnePlus 3 + TPU Gel case but it work with a lot of phones.
U need 4x 4x2 magnets too.
It work on air vents so probably it work in other cars too.
body.stl | 489.1KB | |
down_bracket.stl | 160.9KB | |
top_bracket_locker_x2.stl | 305.6KB | |
top_bracket_x2.stl | 318.8KB |