3D-Printed Water Cooler for Cheapo Chinese 50W COB LED

I saw these cheapo chinese COB-LED on ebay, and i've been told they're getting quite hot.

Now I didn't Test this, I neither have a 3D Printer nor a COB, for now at least. But I intent the aluminum COB-Back to be in direct contact with the water. An O-Ring is planned as a seal, altough stl seems to not render the gap for it. The LED will be mounted by 4 M4x16 screws/bolt, which get hold by a M4 hex nut. The water will enter and exit through a 4/7mm tubing.

If you get grilled by testing this, I am not to blame. No guarantees, this is purely conceptional.