I couldn't find a box to put a relay in, so here's mine.
It allows you to put two relays inside, you can fix them with M2 screws.
The cover holds with M3 brass knurl.
There's a hole on the cover to route the cables to a raspberry and another hole for power cables going to the back.
The case is screwlessly attached to the printer, directly into the t-slot of the aluminium profile.

Relay reference: ICQUANZX ARCELI KY-019 5 V

Enjoy!

Print instructions

Print with support.