Customised version of the back case by ggiavelli which reduces material use and prints easy without supports.
Comes with a separate bung to block the speaker so you can decide whether to install it or not.
If you install it try placing a little sponge in the bottom to dull the sound and ensure a snug fit without the need for glue.
Tweaked in tinkercad
Simple adjustments made in Tinkercad