This phone stand can be used in a variety of orientations, making it easy to find just the right angle. The bumps along one edge add even more available angles to use. 

I recommend printing with a brim. You can change the height of the spacer in the slicer software if you have a bigger phone. 

No Screws required. The spacer should press fit into the holes. If it is loose,  a bit of super glue will work great.