A round fan duct for SR. Tested in version +8.5mm on my printer modded with this part to increase the flow rate using a +8.5mm Volcano adapter by Stefan (CNC Kitchen channel) and a Bimetal Volcano CHT 0.4mm nozzle.
It work better than the standard modded fan ducts, in terms of air distribution: in a cylindrical test flow (70mm diameter) at 200mm/s, cooling with the standard fans and fan ducts present cold and hot zones, instead the ring is uniform.
In the stl files there are the standard +8.5mm clones too.
My slicer settings are selected to achieve lightweight, and the parts (longer ring and standard), weitghts less than the original, without loose in functionality.
In the pdf file there are all the settings: important part is the erase box to modify the up and down surface in the critical part, as in images at the end, but only if you choose the dynamic layer setting, for better definition and overhangs management at the nozzle. In case you use standard 0.2mm the eraser box is less important. Supports are needed due to the curve part that bridges (but if you want try without, report to me in case of success), but with that distance with eSun PLA-st detachment is easy enough.
The part behind the hot part is near, but with a handmade silicone sock (due the non standard shape), at 225 degrees, PLA too is ok in my case.
I didn't tested the standard length, so if there are some problems please report here and if there are other suggestion for all the parts, too.

Is obvious you need to detach the circular fan duct to mount the levelling probe, but with that shape if you want, you can use only two screws in diagonal so, less weight and less work :-) (in a delta in general the bed levelling is less frequent so the problem is in second plane).

Hope someone find it useful.

Cheers