4 inch flanges with spray booth

I needed a flange for an airbrush spraybooth I was building. I designed a simple 4 inch flange and accompanying backing plate to mount to the vapor chamber. I used M6 bolts and embedded the nuts into the backing plate. This is my first upload, so feedback is welcome. Update: Included a zip file with basic construction of the spraybooth. Added a 45 and 90 degree flange for those that need a more flexible setup. The 90 will need support at the front on the build plate, makes sure to support block the inside.