I designed a phone holder for my desk, it can be turned(horizontally) and tilted(vertically) 

1.You need to glue together the phone support(1) and the phone support back(2) 

2.Screw/glue the rotating part2(3) and the table sup.rotating(4)

You can fix on to the with a screw or doble sided tabe if it will be at a fix ange.

I will design a part witch comes to the edge of the table and not needed to drill your tabletop.