I made this as a single bracket stand for tablets. I wanted something simple and fast that could support a tablet on the bed.
The bracket is long so that it has no issues even on soft mattresses, and has a low profile so that it just supports the tablet and lets it sit on its own frame.
An 8mm thick device sits at an 80 degrees angle. Thicker devices should work too, but at some point, the angle is going to be too steep.

Slicing for tablet

For a tablet, the thin part (thin.stl) works nicely and it's sturdy.
With a rough 0.28 layer and 10% fill, it should be printed with ~20g of PLA in less than an hour

Slicing for mobile

The stand will work in landscape mode unless your mobile is small (~70mm is the min height).

20mm Removed because there are some artifacts
If you want to have it up-strait (portrait mode), then you should probably print the thick 20mm part, so that the entire mobile can sit on top of it.

Disclaimer

Don't fall asleep on it. It could snap and stub you :p