Add-on parts for a 7" screen (https://www.amazon.de/Monitor-Raspberry-Portable-Touchscreen-Consoles/dp/B083S6RXDV). The idea was to use the existing screws of the screen to just add on the parts. It worked.
I used this speaker: https://www.amazon.de/Hama-Lautsprecher-Computer-Notebook-Smartphone/dp/B018VONYPY but any 4.1cm speaker will do.
You can print the parts without any supports.
screenLeftSide.stl | 43.1KB | |
screenRightSide.stl | 51.6KB | |
screenStand.stl | 19.0KB | |
screenTop.stl | 19.4KB |