Left fan duct for the ultimaker. Bigger opening, directs air flow downwards, tight tolerances, doesn't interfere with blocks. Works on a stock ultimak...er. Nozzle v2.
Print part, no special instructions, no support.
Remove old fan shround, remove fan from old shroud.
Add 2 nuts onto your long bolts
Slide on printed part
Attach fan with 2 nuts + 2 long bolts
Optional nut on the bottom.
tighten Nuts.
Make sure it doesn't touch your buildplate when your Y axis is zeroed.
It doesn't on mine, but file if necessary.
3d model print parameters
3 standard ultimaker nuts. You should have extras in your parts bag......