Here's a tip for making steel window frames for commercial and industrial buildings. I make scrap metal loads in addition to the other loads I make, and am always examining different objects and materials to determine if there is a potential piece of scrap. I had some old 1/8" X 1/8" wire screen, and I cut it into various sizes to represent window frames for my scrap loads. After they were cut to size, I used the fine wheel on the grinder to smooth the edges. I sprayed them with flat black, and then will bend some of them to represent a demolition project.
I realized that these could also be used by modelers as window frames for scratch building or kit bashing. I'm sure that acetate could be glued to the back. Here is a photo:
