We use a KEY to open the door of our house that’s why I attached an image of a house with a key to represent “OPEN HOUSE”. This creative sign is so simple yet clear and sturdy. The message is clearly disseminated and the OPEN HOUSE logo is obviously seen. I suggest the use of plastic and aluminum material for water resistance and also light to carry. I also suggest the use of lighting effect so that it can also be seen at night. Thank You! 🙂