My son wanted to get an alarm clock for his room which preferably plays MP3s. MP3 players are surprisingly expensive at 40 CHF for a 4 GiB model so I picked up a used Moto E 2nd gen phone for 35 GBP, loaded a stripped down version of Lineage OS on it, and designed a 3D printed a stand:
I’m quite happy with how it turned out. The phone is just an alarm clock and MP3 player as the other apps are either not installed or (like the Play Store) behind Lineage’s protected app feature. This gives ~5 GiB of free storage for songs. The battery lasts for >= 5d as well.
I’ll do one more revision to build a right angle USB cable into the base for easy charging.