There are a lot of DIY phone mounts for a tripod but probably not too many more simple than this one. The advantage of this mount over the others is that you don't have to remove your phone from its case. And you can orient the phone vertically or horizontally.
Parts count is very low and time to build is a few minutes.
Disadvantage: yes, the clothes clip blocks a part of the viewing screen. Doesn't bother me too much.
The last photo is a long exposure I took of my night flying radio control wing. The easy phone mount made it simple to set up the camera.
Step 1: Find a Few Parts You May Have Lying Around the House
1 angle bracket - can just be a 90 degree angle bracket of just about any size or shape. Aluminum is easier to work with than steel as you may have to drill or widen a hole. I had an aluminum servo bracket that already had all the hole(s). The bracket needs to have a hole drilled in the bottom short section which fits the bolt on your tripod camera mount.
1 large springy clothes clip.
1 nut to fit the bolt on your tripod that screws into the base of your camera. Can also be had at hardware store. I had one from a small portable tripod.
1 optional bolt and nut if you want to more permanently mount the clothes slip to the angle bracket.
Step 2: Portable Mount Configuration
The portable mount is created by just mounting the bracket to your camera mount with a nut. Then hold your camera to the angle bracket by clipping the clothes pin over the top.
Step 3: Permanent Mount Configuration
The more permanent mount is made by drilling a hole in one of the clothes clip handles to a matching hole in the longer side of the angle bracket. Insert bolt and nut and you are finished.