Hello fellow brewers,
I finished my fridge build a few days ago and wanted to share my results.
I used this fridge (Bomann VS-3171):
https://www.bomann.de/products/de/Bomann-Elektro-Grossgeraete/Vollraumkuehlschraenke/Bomann-Vollraumkuehlschrank-VS-3171-weiss.html
Bomann sells quite inexpensive fridges in Germany, but it should be robust enough for my purposes.
I began by checking out the fridge thermostat:
I am not an expert so I googled a bit and tried around a bit what to do, to go around the thermostat completely. I had to connect all the wires (compressor, light, fridge fan) except ground (yellow/green) for that.
Behind the thermostat enclosure I drilled a hole in the side wall of the fridge (luckily only insulation) for the fridge sensor and beer sensor.
I used the SSRs from the Brewpi shop to switch the fridge compressor and my heater. this is where I mounted the SSR:
I used this reptile cable as a heater:
The cable from the heater is routed through the condensation run-off hole, so apart from the hole in the side wall (for the sensors) I didn’t have to drill.
This is the inside of the finished build (you can see my first brew already fermenting 
):
What you can not see in the picture is the 120mm fan I mounted beneath the wood panel. I just connected the fan to a 12v supply, so it’s basically “always on” (well not really, I can pull the plug out if I want). it has a switch where you can choose from 2 speed settings for the fan.
So far I am really happy with this build. I’d like to switch out the reptile cable for a tube heater sometimes (mainly to save some room, but I’m having a hard time to find a fitting one here in Germany.
Screenshot from my first brew:
