simple case For 4 ch relay board from amazon MHCOZY brand 

I have included fusionn360 and step files for the housing and the board to use if you would like to modify mine or make your own!

Please note you may need to snap off the extra strip of board in front of the relays to make it fit. this strip of board does not contain any electrical connections it is just an extra piece of scrap material left over from the PCB production process. the board is already scoured so you can easily remove it by bending with a pair of pilers