Draw a drawing of the castle that you want to do. Determine what parts it will contain. Label the dimensions of each part. If you find it difficult to come up with the structure of the castle, look for his pictures in encyclopedias or on the Internet.
As the material, take the colored cardboard. Then later you will only have to finish small details.
Start the erection of the wall. It should surround the whole structure. As a built-in tower, you need to make multiple cuts of the same height. On the cardboard the required length and mark the height of the wall, draw a line parallel to the bottom edge of the sheet. Above the same line, check the thickness of the wall and again put the height. Bend the workpiece along the intended lines. The top of the wall crown teeth. Do them separately in the form of cubes, the side of which is equal to the width of the wall. Make a scan of a cube of six equal squares. Add valves to connect the edges together. Glue the cubes and stick them on the wall at the same distance from each other.
Towers of the fortress can be either cylindrical or rectangular. To make the cylinder, cut out the rectangle and glue its sides. In the second case, you will need a scan of the box. A cylindrical tower complete with cone-shaped roofs, the tops of the towers should consist of four connected triangles.
Collect all the elements of the external "layer" of the castle. In the side faces of the towers the holes, insert the parts of the wall and secure with glue.
Inside the ramparts, "build" residential and business premises. Their number and shape depends on the era and place of construction of the castle, which you copy. In the center put a cylindrical or polygonal donjon – the main room. This building must be the highest. It can be linked with lower buildings or make offline.
Ready lock paint. On the ramparts draw the Windows and loopholes. On the castle – Windows and doors of various configurations. If your model is big enough in the Windows you can draw the silhouettes of the inhabitants of the castle.