It’s story time! 
As most of you will know, I take dust removal fairly seriously, and one component of my setup (are two!!) ten inch hydroponics exhaust fans, which create enough air changes per hour to meet most OH&S requirements, and more importantly create a negative pressure which keeps all that fine dust out of the house and my wife’s sewing corner.
A long time before I had a 3d printer (2019 to be precise) I needed to install one of them to exhaust through a pair of six inch outlets, so I developed the ductwork on a piece of 3mm mdf, scored it and made a “Y”, sealed with some epoxy and decorated with some real estate advertisement decoupage.
Apart from the rather unfortunate location in the very back corner of the shop, facing sideways, it’s served quite well for six years, but I had other plans!
There’s plenty of science that shows that a proper bellmouth opening improves the efficiency of any duct, and I have a collection of them on my Printables dust collection pages so a few years ago, when I first started dabbling with CAD, I started working on a printed duct and some mods to the setup which would turn the mount at a better angle to the room.
The cute little trussed hanger was going to be built on the LR2, which probably gives a fair idea of how long this has been in the works.
Anyway, no one can joke about it any longer - today I finished the mods, new 3d printed duct, bellmouth (my new parametric design suits any duct from 90-300 diameter) and a cute little domey thing on the fan axle cap, which may or may not be scientifically designed.
I don’t know if it’s going to change things or not, but I’ve had fun building it and it does add a little eccentricity to the place. Yes, that is the LR3 with the covers off - I’ve been measuring things.
Just to add a bit of scale - the inlet diameter is 170mm, the overall dimension around 360, and it’s a slightly more elegant shape than my previous efforts. The fancy CNC cut mount? That may, or may not be in the works, time will tell.