Before any of the electronics happened, this project started as a doodle: what if a wind turbine's blades lived inside a duct shaped like a de Laval nozzle — wide at the inlet, narrow in the throat — instead of sticking out in the open? I don't own a 3D printer, so step one wasn't design; it was logistics: finding somewhere that would print two oddly shaped parts for a hobby project without charging me a small fortune or asking a hundred questions about tolerances I didn't have answers for. Took a few tries and a few "sorry, minimum order" replies before one local shop agreed to just print what I sent them.

I modeled everything in Blender, cylinder and funnels alike, and printed two identical white funnels first — one for the front, one for the back. Only after holding both in my hands did it click that they shouldn't be identical at all: the front one needs to be more rounded, almost ball-shaped, to actually work as an air inlet, while the back just closes things off.

So I tried to model that rounder front piece myself. I got the curve wrong. Not subtly wrong — wrong enough that when it came back from the printer, it looked like a funnel that had given up halfway through becoming a sphere. I ended up taking a hacksaw to it, cutting away the parts that didn't belong, basically sculpting the shape I should have modeled in the first place.

That fixed the curve, but now the piece was too small in every direction. My fix for that was somewhere between improvised and ridiculous: I cut strips out of soda cans and taped them on with reinforced duct tape, widening the smaller opening and stretching the whole piece longer, one strip at a time, until it finally matched the rest of the housing.

It works, and structurally it's solid; but if I rebuild this, that front piece is the one part I'd model correctly from the start instead of eyeballing it and fixing it with hand tools afterward. Lesson noted for next time: model it more elongated and slightly oversized to begin with. The full write-up with dimensions and photos is linked in the sidebar, for anyone who wants to skip the hacksaw step entirely.