How to play music you own on an Amazon Echo

Amazon's Alexa is becoming less hospitable to people who prefer to buy music instead of just signing up for a music subscription service such as Spotify. Until recently, Amazon Music Storage was the best way to stream your personal music collection onto Alexa devices--provided it was encoded as MP3 files. But in December, Amazon stopped supporting new uploads for the free service; it stopped accepting paid subscriptions a month later. In January 2019, Amazon will shut down Music Storage entirely, rendering your MP3 collection inaccessible on Echo devices unless you purchased the songs directly through Amazon's digital store. To play your own MP3s (or music encoded in other formats, such as FLAC) on the Echo or other Alexa devices, you can still use Plex or My Media Server for Alexa, both of which allow you to stream songs that you've stored on another device.