This is a work in progress. I was unable to finish it due to my house flooding. I will re-visit it someday and repair the one hole that is torn.
This adapts a 40 mm radial fan to the blower fan opening of the Hero Me V6 Fan Duct It works great as is, it's just the inside of the hole that secures it to the hero me up top is a little wonky. Wont affect performance or attachment because you do not even need the top hole.
Also note if you put a screw in the top hole, you will need to grind the head of the screw down to a smaller diameter. Otherwise your fan wont be able to sit flush