I made an adjustable phone holder.

5 inch piece of 1"x 1"x 1/8" angle, ripped one edge to 1/4". Bent the cutoff piece 1" in at slightly more than 90 degrees. Drilled a hole and welded a nut on the back. Hand sanded with 100 grit paper.

Made sure the screw was low enough to work in landscape orientation.

Top of the stand holds the phone at a pretty good angle in portrait orientation but if it needs to be more upright the screw works like a champ.