Create a detailed 3D model of an ancient Mayan stone block for the month July. The cube is about 500 mm per side, with realistic weathered stone texture and deep Mayan carvings on all four vertical faces. The top and bottom surfaces are smooth, flat stone to allow stacking. Use high-resolution detail showing erosion, chisel marks, and patina. The model must be watertight, physically accurate, and suitable for 3D printing or CNC carving.