This is a shelf or wall mount, for a generic MP3 player like https://www.amazon.com/gp/product/B07Z81GNWR to hold the player for use on a home stereo system, for example. It has slots/holes in the bottom for access to the USB cable jack, headphone jack, and microphone. I mount it to my wood shelf with 3M Command Strips so it can be removed without damage to the shelf.

If your printer can handle about a 1/2" (12.5mm) horizontal span, this can be printed without supports. My Lulzbot Mini 2 prints it fine with no supports. The source FreeCAD file is included, in case you want to make changes.