Well the window itself came from Menards. It is just a residential sliding window. The size is 36″ x 48″. The metal studs in this trailer are 24″ on center so when I cut my opening I only needed to cut through one stud. I then made a 2×3 frame to reinforced the opening. I attached the 2×3’s to the studs on each side. On the top and bottom of the framing in between the vertical studs I attached 1×2’s to the upper and lower sides of the 2×3’s which I was able to screw the plywood wall to for stability. These 1×2’s are in the walls ( not visible) but are attached to the 2×3 framing on top and bottom. The 2×3 framing was installed flush with the exterior skin and actually sticks out inside the trailer by about 1 1/2 inches or so. It’s been a while so I might not be exact. I then priming and painted the framing. The window has a installation flange with mounting holes all around so I attached the window from the inside of the trailer onto the inside edges of the 2 x 3 frame. I then trimmed the outside with aluminum angle
Installing from the inside like this indented the window from the outside which gave me a 1 1/2″ ledge where I was able to mount the shocks and hinge for the windown awning that I made.
For the awning itself I used 1/2″ inside measurement aluminum channel for the framing. All the ends were miter cut at 45 deg angle. I sandwiched a piece of either 1/4″ or 3/8″ plywood ( cant remember now ) inbetween .040 aluminum sheet for the exterior side and a piece of FRP for the interior side. Each corner of the plywood, aluminum and FRP were cut so that I could fit a smaller piece of channel ( which were cut at 45 deg angles ) inside the corners of the 1/2″ channel. After those sheets were sandwiched, I slipped the 1/2 channel over the sheets one side at a time. After one side was on I placed the smaller cut channel pieces in the corners of the 1/2 channel untill all were installed. Once all sides were over the sheets and in place I drilled holes through the channel where the 45 deg angle met all the way through the smaller pieces that were placed inside the corners. I then pop riveted those pieces together. I did this on all corners and on both sides. I should mention, that the 1/2 channel was hard to slip over the sheets but it straightend out the bend ply wood. Also, I used silicone in the channel before I slipped over the sheets and after very neatly around all edges. Once complete, I used a stainless piano hinge to install to the trailer window opening. I then installed gas struts / shocks to lift and hold the awning open. I also installed cam locks and a handle.
I hope this helps a little. I am rushing to write this before I leave for work so just ask if you need clarification on something else.
Good luck and thanks for checking out my thread.