A modification of the standard MK3 Fan Shroud to allow mounting of a second blower, for extra cooling power.
Also provides a clear view of the nozzle, so you can watch the filament being laid down.
Drastically improves overhangs, and bridging has been tested without failure up to 280mm (as much as I could fit onto the bed)
This object was born because I wasn't happy with the uneven way in which the stock shroud on the MK3 (R2, at the time) cooled parts, such that overhangs only really worked when facing the front of the bed. Adding a second fan for more power seemed an easy solution, and early iterations of this design did just that - more power through the same shroud. During this process, I noticed that I could significantly improve the user experience by creating a clear view of the nozzle and heatblock. I used CFD to optimise the air pathways to ensure that the jets converged just at the spot where the plastic is being laid down for maximum cooling, without any risk of inducing a thermal runaway error. As the test results show, performance of the printer is significantly improved. This won't dramatically change the quality of your prints, but it represents a bit step up in reliability for complex parts, while allowing you to print simple parts even faster.
N.B. The second fan does not need to be a "three wire" type - simply join the red/black wires of your new fan to the red/black wires of the existing Prusa fan, and you're ready to go.