Summary

I remixed thing 588894 for an old LG G4 android smartphone You could probably resize it for your old phone.

I used an app that allows the display to be dimmed and also gives one-touch access to the system alarm clock. See the app here: https://play.google.com/store/apps/details?id=com.bojankogoj.giantclock

The case was designed in one piece (see SCAD and STL files). To allow insertion of the phone, I used my Bambu slicer to break it into two pieces (3MF file) with alignment/assembly pegs.