This is a 30A relay case that can mount to 2020/2040 extrusions.

Backstory: I wanted to control mains power using Klipper so I got a 30A relay board. With little space in the electronics compartment, I designed this case and mounted the relay towards the back left of my Ender 3 v2 with this case, which is closest to the power supply..

Creality

Ender 3

Doesn't Matter

Doesn't Matter

.2

20%

Since the relay does not generally generate heat, PLA should be fine but up to you.

2 - M5x6 Button Head Screws
2 - M5 T-Nuts
1 - 30A Relay

The filament I used is Overture Black Matte PLA

1. Put the Screws and Nuts on the case
2. Mount it to where you want it
3. Put your relay in the case
4. Wire up the relay (There are plenty of writeups on this)
5. Put the lid on. It's press fit so it should stay if print went OK

Optional
I used black braided sleaving to keep the wires together and make the exposed wires look sleeker.