1_6_to_3_4 Duct Adapter

This adapts from one 6 inch duct to three 4 inch ducts, with a single part, in a fairly compact form factor.

By design, this barely fits in the build volume of an mk3s+.

The .f3d is included.  You may want to reduce the wall thickness some, but if you do that, take care to check how the slicing turns out re. gap filling; I was having some issues getting the thing to print using mostly perimeters + gap filling, so I finally resorted to slightly thicker walls that have just a little bit of 100% infill in every wall, just to avoid the slicing weirdness.  I was using PrusaSlicer 2.4.  Maybe by the time you read this PrusaSlicer will be smarter about varying the width of a gap-fill extrusion along its length to allow smooth transition from N perimeters wide to N+1 perimeters wide without ever extruding over itself or creating zillions of little short extrusions like a dotted line, but until then…

Maybe Cura can slice better with thin walls whose thickness varies slowly; haven't tried.

The .f3d is mostly parameterized, so might be able to create a 1 to 3 splitter with different ODs, while keeping the no-supports-needed property and the max overhang of 45 degrees, but I didn't try varying the parameters to test out the math…  Hopefully it'd work.

I used PETG, but PLA would probably also work fine assuming usage within PLA temp limits and not too much long term deformation stress.

This print may require pants, to taste.