I guess I was a bit ÜBERmotivated. Excuse my german. So the plan was to get 4 ports with switchable voltages. But the connectors for banana plugs were that big, that I decided to use three wires on one.
This is definitely a temporary design, I've already worked on the 2nd version of it (with not so many banana plug terminals and will hopefully be able to get it laser cut somewhere. Maybe I'll throw in a USB plug.
The result so far... well... I got one port with 3/4 channels or the other way around. And maaaaaan, this old supply is loud.
I'm not sure how hot the resistors are allowed to get, but I'm planning some heat absorption and involving a fan to keep those monsters cool(er(ish)). The gauge of the wires is set to accept around 1.5A but I used 2 wires for safety reasons.