I took Lionel 610 cars, restored them to look like Polar Express cars, made them Ryder Express cars for my Grandson and put all his family pictures in the windows. For the Photo's I made a pattern of the windows , sized the photo's to fit and made a color copy of all the pictures in one strip. I also added 2 additional light bulbs in each car to even out the lighting. If you don't want to go to all that trouble just use frosted acetate from an art store like I did for Lionel Diners I created from 610 cars. I straighten the pointed tabs, sometimes they break off so I put a small piece of double sided tape around each window frame to hold the new window in place.