You will need a phone case with a magnetic back in order to use these.
I made a few versions of a phone mounting system I've been working on. The holes on each model is designed for 5 mm x 12 mm ceramic magnets, which I would recommend epoxying in place. Printing the flat back versions will allow you to glue it to a different mount (pictures show how I used CA glue to attach one print to a car air-vent clip solution. Do note that vibrations could cause your phone to fall even with these magnets, so be warned.
Also included is a print (PhoneMountClamp) that is compatible with yyh1002's modular phone mounting system: https://www.thingiverse.com/thing:2194278
Final note: ceramic magnets are somewhat dirty by nature, so I would suggest putting something over the magnets to keep your phone clean. As well, I used a tape with a more adhesive exposed side (electrical tape, duct tape, etc.) so I could have a removable cover that also helps stop the phone from sliding on the mount.
PhoneMount.stl | 55.4KB | |
PhoneMountClamp.stl | 252.2KB | |
PhoneMountv2.stl | 65.7KB |