Don't have your own 3D printer? Check at your local library! San Diego County Library has 3D printers you can use for just the cost of the filament. :) Contact your library first to see which branch has a printer, and what are their details. :)

I didn't want to pay $130ish for a miter saw hood, so I bought a paint spray booth tent for $20ish (https://www.amazon.com/dp/B0CQC75SWY). It had screen in the back so I sewed that shut. I then used the tent's loops and strings from shopping bag handles to tie the top loop to the saw handle, the floor around the front of the saw, and then the sides to existing holes in the saw frame. I used mostly taut line hitches to tie everything in place.

I made a flange to connect the 2.25" diameter shop vac hose in the center back of the tent. The flange has little arrows by the holes so you can see which holes align with which holes in the two pieces. I used a sharpie with the flange to draw the circle and then cut it out with a scissors. I used M3 18mm screws and M3 nuts to attach the flange, though they're a bit too long, but I had them laying around so I used them. They use an allen wrench that I also had laying around. Shorter would be better, but the M3 10mm ones I have a ton of were a little too short. I punched holes in the tent for the screws with an exacto knife, and then pushed the screws through. They're too long, but it made it a little nicer to have some extra length when I was negotiating getting the nut on.

I then attached some 1.25" diameter hose to the dust output (with hose adapters I already had) on the saw and ran about 3.5 feet worth through the back, into the flange, and about a foot or so into the shop vac hose.

Gave it a test and it seems to work! The tent is big enough and the ties are flexible enough that I can slide it, and turn it, and the top loop tie to the handle makes the tent come along for the ride.