In my old apartment, I wanted to have a glass roofed hallway, the only problem was, it was on the 3rd floor of a 4 storey building, so I faked it.

Step 1: Painting Clouds

I started by painting the ceiling and parts of the walls. It didn't have to be very accurate, since it will be all blurry afterwards anyway. Just blue and white fluffy clouds.

Step 2: Adding the Trusses and Lights

I made the trusses out of strips of MDF. A slit was cut down the middle and glued together to form an I-Beam. Then I made the triangular truss segments. Everything was painted with iron paint (with iron particles in it) and a mixture of black and silver acrylics in the less visible areas. I also made an L-shaped beam out of 2x4s and mouted them to the walls each side to rest the trusses on. The Trusses were conneted at the top with 2x4s (all unpainted in these pictures)

a row of daylight neon tubes was mouted on top of the roof. I would use LEDs today, but back then they were too expensive.

Step 3: Adding Windows and Details

I ordered 24 macrolon (plexiglass) panels through a company I know. They were leftovers from exhibitions, so they had scratches and marks, but that didn't matter and it was cheap. ?

I found a picture of an Industrial window on textures.com

https://www.textures.com/download/windowsindustria...

I made a Photoshop script that copied the window panes to a new file, scaled it an printed it on clear, self adhesive sheets of laser-printable stuff. I used up loooots of sheets and loooots of toner, but it was worth it. I stuck them to the macrolon panes and added the window seams with electrical tape.

The panels simply rest on top of the beams, so they could be taken out when needed (i.e. to change a light tube)

Remaining gaps I closed with strips of foamcore board painted with the black/silver acrylics mix.