I'm starting to add some "smart" devices to the families house. This is one design iteration for a case that can contain some multi clamps, a 220V -> 12V converter (I'm using 1A USB power connecters for this), a single channel relay and a WEMOS D1 mini (perhaps a NodMCU)
The design is straight forward, no fancy mounts or places for screws, because I'm using parts that I already have. So relays, clamps and converter might change from build to build. Just hot glue in the components and snap the case together.

If you're interested in this one, you might want to check these, too:

https://www.prusaprinters.org/prints/24552-wemos-d1-mini-temp-01
https://www.prusaprinters.org/prints/17287-wemos-d1-mini-plug-04
https://www.prusaprinters.org/prints/16723-wemos-d1-mini-plug-03
https://www.prusaprinters.org/prints/16607-wemos-d1-mini-plug-02

Print instructions

Category: DIY Print Settings

Printer Brand: Prusa

Printer: i3 MK3

Rafts: No

Supports: Yes

Resolution: 0,25

Infill: doesn't matter

Filament: Das Filament PETG schwarz
Notes:

Support is only needed for the cover, not for the bottom.

Post-Printing

Wire up the components, hot glue the components to the bottom plate (roughly labeled) and click the bottom and the cover together.