Dana, it would be great if you shared what you have developed!
I made mine like Lydia and they are holding up fine. We have taped them to the windows to use. Also, students take them home and make the drawing of their room or view from window as basis for enlarging for a painting. Afterward, we look at artist examples who have been inspired by the same subjects.
"made using some overhead transparency frames ....I just printed out a sheet with the "quadrants"
on it, then photocopied it onto transparency sheets, then taped them into the frames. "