Sure. Here they are I think. Not at my upstairs work computer right now but I’ll try to check the hardware size and edit this post. Don’t overextrude the nut holes are pretty tight by design so they don’t slip out.
You should see how the filter just ‘slides’ onto the duct at the fan, so to get airflow you’ll have to notch out about 1/4 of the cylindrical wall, in whatever orientation you choose.
filter_frame.stl (844.2 KB)
filter_lid.stl (732.4 KB)