Wanhao Duplicator 4S part cooling fan duct (and other clones)

This is a remix of fwiffo's Active FAN BackCooling. I would like to thank fwiffo for designing the BackCooler. It cools the filament from both sides efficiently, while providing a good view of the nozzle. Unfortunately, the original model has several problems in my opinion. The first one is with the mounting. The fans and the duct are only secured with friction, over time they shake off. The second problem is the duct in some points has too thin walls. that result in holes. I tried to fix both i