If it was me and no OEM shroud was available, I’d be inclined to just make one. Anything flat, formable, and non-conductive should work for prototyping (I’d probably use card stock), but paper is a fire risk so don’t use that for the final “product”.
Not if it’s sealed
The idea is that there’s a dead spot in the center of the fan and most SP fans blow mostly outward so it evens the spread by spacing it. As long as it’s mostly airtight, you don’t lose pressure
The reason I ask “DIY or buy” is twofold:
Whether the time required is worth it (mostly already spent that)
and
Whether the extra surface area of the corners is worth buying one for, since my DIY shroud is still a circle.
