PA28 yoke clamp
This handed pair of clamps fit on to control yoke of a PA28 aircraft and provides a flat plate to which you can glue a phone or tablet holder of some kind (or anything else, I suppose). In the photo I have glued a holder for a Hudl 2 tablet.
The plate is angled back a bit so you can see the screen.
OpenSCAD source is attached - improvements gratefully received. I have tested it and it works although a little too easy to unclip if you bash it form the bottom. The tablet stayed firm throughout manoeuvres.