Building an MP3 player with Arduino is extremely easy. We use the DFPlayer mini in order to build a simple MP3 player. The MP3 player has 3 buttons, in order to Play/Pause, to load the next song and one in order to load the previous song. In this video we are using an Arduino Uno, but you can use any Arduino board you like.
Arduino Project: MP3 player using Arduino and DFPlayer mini MP3 player module – [Link]