Find a good reference image of a mosque you would like to re-create. Examine the elements of the structure -- the walls, windows, towers and dome. Look at the different proportions and height of these elements as you define the dimensions of your model.
Cut the Balsa-Foam in equal-sized rectangular shapes large enough to include all the elements of the mosque. Use a large steak knife to make large cuts. Dry-fit the pieces of every section you build first to make sure everything is cut to the right size before gluing. Stack and glue the foam rectangles together to create the basic shape of the building. The outer edges will be the wall of the mosque.
Build the large prayer tower separately by forming it out of foam. Glue small sections together to form the large dome that will go on top of the main roof. Create the rounded top using rasping tools. Make sure it is perfectly round. Pull the rasping tool over the foam at different angles to remove thin layers. Keep turning the piece in your hand as you rasp to create the round shape.
Shape the rounded dome-like roofs for the small towers around the central dome, as well as the main prayer tower. Turn them in your hand as you shape them with the rasping tool until they are the correct size. Dry-fit the pieces, and then glue them into place.
Cut out the windows around the bottom of the dome using the scalpel.
Cut more pieces to form the small towers on each corner of the roof around the dome and use the rasping tool to make the rounded walls. Make small cuts with the scalpel to shape the openings on each tower, just below the small, rounded domes at the top. Form any rounded protrusions from the walls of the mosques. Shape half-rounded pillars that you can glue to the walls.
Cut the small wall that runs along the top edge of the roof. Slice small strips from a foam sheet to create the walls. Glue them into place along the edge of the roof. Cut out any windows in the wall of the mosque. Cut them in about 1/2 inch and flatten the inside to represent the glass.
Complete the shaping of any curved edges with the rasping tool. Also use this tool to blend the lines along glued connections and shape horizontal ridges in the mosque walls. Use a straight-edge to guide the tool in order to carve straight lines. Glue the towers and the dome on the corners and the roof of the carved mosque. Make sure the large tower is perpendicular to the roof.
Create smooth surfaces using sandpaper. Finish any detailing and use a brush to remove shavings and particles from the model. Use a paintbrush to coat the model with white latex paint. Use more layers to create a smoother finish. Use blue paint for the large and smaller towers, including the dome, and black or gray paint for the windows. The exact colors depend on the particular mosque you are creating.