Here's one I'm working on:
Dual 360mm radiators, tied to a 5 AMP 12-volt pump with a 20 AMP PWM motor controller. For a water cooling setup for my computer. Currently, a dedicated old computer PSU runs just the motor.
I don't have any better pictures at the moment. One problem I've run into is the motor is super loud so I'm thinking about building an acoustic insulating box for it much like some people do for air compressors on YouTube. I might also upgrade to four radiators.
I originally had a car radiator planned. But it's so fragile and unwieldy in my small house and the fitting adapters alone have cost more than the original car radiator. So I'm putting it on hold for the moment.
Ideally, the radiators should be enough to run with natural convection. But even a soft breeze would be completely silent and enhance the convection immensely.