The original upload only contained a single .3mf file. I opened it with PrusaSlicer and exported each of the 3 components as individual .stl files. No other modifications were made. Duct should supposedly be printed in the orientation provided with tree supports on. Use a generous brim, given the fact that the duct barely touches the buildplate.
Some slicers don't interpret .3mf files very well, .stl is more accessible. Commenters requested .stl, so here they are! Still hoping original creator will upload .step file so it can actually be remixed properly.
The author remixed this model.
The original upload only contained a single .3mf file. I opened it with PrusaSlicer and exported each of the 3 components as individual .stl files. No other modifications were made.