Remember these things? I used to paint sun catchers like this with my sisters when I was a kid, and now my kids are painting them :)
Sun catchers make great stained-glass windows for a cardboard dollhouse. When your paint is dry you can trace the shape of your sun catcher on the wall of your dollhouse with a pencil and cut it out with a knife. Use hot glue to secure your "window" in place. Easy peasy.
|Fig. 1 - cut an opening for your window.|
|Fig. 2 - Glue in place with hot glue.|
I haven't put a "stained glass" window in a dollhouse recently, so I don't have any photos for you. If you use this technique, please post pics of your dollhouse on my Facebook page!