2A SSR module box
This box is for the small 2A SSR modules with screw terminals widely sold on eBay for use with Arduinos and Raspberry Pi. See the attached photo to be clear you have the same module.
I have two of these SSRs controlling power to my Creality Ender 3D printers through the PSU control plugin for Octoprint. I carefully strip the cable sheath then break out just the live connection to the SSR.
The screw holes are sized to work with ~3mm drive screws commonly found in PCs as I had a load in my spare screw box. Use two screws to hold the module in the base, then two more to hold the lid on.
The cable channel is sized for a typical IEC mains lead and lightly grips it. If your cable is thinner, a little glue may help.
The vent holes in the top are nominally for ventilation and also so you can see the status LED, but probably unnecessary. If you don't want these, print the 'without holes' version.