Smallest temperature controlled fermentation chamber

[LazyBrewer]

What is the smallest temperature controlled fermentation chamber/kegerator anyone here has ever built?
I am working on a project converting a secondhand 20 liter Peltier mini fridge to something I can use for for smaller 3-4 liter tests (pressure fermenting and serving/bottling from the same vessel).
Yes, I know all about the cons with Peltier cooling but the good thing is that you also get a way to heat the chamber when needed (very useful during the winters here in Finland because we have +10C in our heated garage at the moment).
Have already passed the proof of concept stage with only the fridge and the next step will be to drill holes for CO2 and liquid posts on the outside of the fridge (using carbonation caps as posts).
One cider, one carbonated mulled wine and one lager already fermented in the fridge.
I would say that this should work like a charm because in theory you should be able to get 18C under ambient or maybe 30C above, with these cheap fridges.
This means that in the winter I have no problem cold crashing in the fridge and every normal fermentation temperature is covered all year around.
In the summer cold crashing might not be an option but I can live with that as long as I can control the fermentation temperatures.
The only problem I had was figuring out how to control the temperature without drilling an extra hole for an Inkbird probe.
Solved this by using some cheap Tuya "toys" (a wifi thermometer and a wifi controlled power socket).

If anyone has built an ultra light/mobile fermentation chamber/kegerator I would be very interested to hear more about your project and what you learned from it.

 

[LazyBrewer]

Forgot to mention that I can fit one 4l oxebar keg or one 5l steel mini keg with a NukaTap mini and a 16g cartridge with a regulator inside the fridge. This is fine but the iGulu was the reason why I started planning this and the only problem with the iGulu in my mind, is that they did not use standard ball lock connectors. I guess that they had their reasons for this (saving space, cutting costs etc.) but I always want to be able to connect whatever I want to the kegerators, keezers, jockey boxes and my other DIY projects. With posts on the outside of the fridge I can connect any spunding valve, bottle filler or tap/tap tower solution I like. Everything needs to be as modular and standardized as possible. When something breaks or you stumble on a better solution, you always want to be able to replace the parts. My solution will never be fully automated as the iGulu but this is not a problem for me.

 

[wide eyed and legless]

I use a small shed which I insulated, it allows me to store and keep my bottles below 20C and I can ferment multiple brews. The temperature is controlled by a reverse cycle air con, cool mode for summer and heat for winter.

For going below 17C I use one of these on special at the moment for $199