Here is how I have modified a Car Radiator to fit 12mm hose,
Original hose fittings was too big.
cut them off
Homemade brass tube fittings
Made to fit exactly into the radiator.
The hole inside the brass fitting is as big as possible.
The hose is 12mm inside.
It fits really good on the brass fitting, it is 13.4mm
The paper is A3 size so you can imagine the radiator size.
After gluing, now ready to be installed.
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