This is a wildly experimental design. I wanted to experiment with different part cooling duct designs on my MPSM V1... but after breaking a hot end thermistor lead while unmounting and remounting the fan on different shrouds, I decided I needed to make a modular fan housing with which I could change part cooling ducts without messing with the fan mounting.
This is the initial cut, A clipless design with one (uncreative) duct, and a shutter for printing PETG which doesn't much like part cooling. I'll add other duct designs as ideas bubble up.
I'm running a V1 but have swapped out the heater block for one from an E3D V6 and I have a silicone rubber boot over the heater block. The hot end heatsink is still the original. All this means that you may have to tweak the duct part if you're using an OEM heater block.
Stay tuned for future changes (or testing results that indicate this may be a terrible idea).