This is a very simple case for the wren keyboard. Basically it is a box with cut-outs for the connectors.
It improves the sound though an gives some protection.
To assemble I removed the bottom plate from the keyboard and screwed it to the case with the M2 screws that are used for building the keyboard.
You can find the keyboard here: https://github.com/oliviahanley/wren-keyboard. I only designed the case.
The author marked this model as their own original creation.