I'm including the fusion 3d export here so you can adjust the angle as necessary. 

The exported .step, .stl and .3mf are all a 90 degree corner.

Screen framing is something like this: [https://www.amazon.com/M-D-Building-Products-14105-Screen/dp/B0947CSX8W/ref=sr_1_3?crid=2B7DNJ9GAW1I3&_encoding=UTF8&tag=jpn6270c-20&linkCode=ur2&linkId=0d5361a472f6fabecea1a8102571d64d&camp=1789&creative=9325](https://www.amazon.com/M-D-Building-Products-14105-Screen/dp/B0947CSX8W/ref=sr_1_3?crid=2B7DNJ9GAW1I3&_encoding=UTF8&tag=jpn6270c-20&linkCode=ur2&linkId=0d5361a472f6fabecea1a8102571d64d&camp=1789&creative=9325)

I got mine at home depot.

[https://www.homedepot.com/p/Screen-Tight-5-16-in-x-84-in-Aluminum-Screen-Frame-MSCF5167/100069982](https://www.homedepot.com/p/Screen-Tight-5-16-in-x-84-in-Aluminum-Screen-Frame-MSCF5167/100069982)

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