[gafftaper]

You can do this with Muslin too. Instead of painting it, you starch it with hot starch to size the drop. Then to color the design you use dyes. The combination will leave you with a drop that you can see light through. For the leaded parts and the frame you use paint. The paint will be opaque but the dyed part translucent.

Also do some window cling research. There are getting to be more giant window clings available in fake stained glass. My local Home depot caries a couple of options.