First, if you haven't yet seen the wonderful photos of giant quilt blocks painted on rural barns, tap "barn quilt photo" in your search engine and enjoy!
I don't have a barn and I live in town, but I do have a garage, and want to replace the badly weathered "welcome" sign, which is a separate round disk that is painted and attached with a single nail. Thus, I was thinking a painted quilt block would be nice! 24" by 24" would be a good size. Because of the siding it would need to be painted on a separate piece of wood or whatever and then attached. Has anybody done this? What materials did you use? Any tips?