To 3d print this model, I suggest 3 or 4 perimeters, no support, infill at your discretion and at least 300 microns of precisions.
This is my first upload on thingiverse. It is a fan duct dedicated to various application, but it's main purpose is to replace and/or extend a traditionnal 120mmx120mmx38mm fan to a 4 inches piping, such as a 4 inches blower fan, etc. It is designed to fit with the same screws used with the original fan, you won't need to replace them for a shorter or longer version. In my case, I will be replacing the stock fan ( exit end) of a Antminer S9 with this duct and I will fix at the end of it a 4 inches industrial blower to lower noise and also greatly increase cooling. I hope this will help you, if you wish to 3d print it, share it or modify it for your personnal use, feel free to do so. If you like it, give it a like, this will be my reward! I apologise for the bad english by the way!
Happy 3D printing AND mining!