Abstract: A structure modeling device for the creation of sand figures, including sand castles, that provide structural stability to the resulting figures and aesthetic enhancement. The main structural member includes a central body member and at least two fin members extending outwardly therefrom at an angle so that sand is cooperatively received and its weight directed downwardly to enhance the interlocking engagement with abutting members. Other structural members permit a user to form diverse building shapes, such as columns or cones. All of these members have fin members that hold sand or other granular material and direct its weight downwardly through the engagement means in order to enhance the stability of the resulting figure or structure.