1. The problem asks to visualize the 3D shape formed by two concentric squares positioned vertically with lines connecting them, enclosed in a larger rectangle, and considering the cube has thickness, making it a solid. 2. Start by understanding the 2D layout: two squares, one inside the other, aligned vertically with connecting lines. This suggests a 3D shape formed by extruding the squares along the vertical axis. 3. The two concentric squares represent the top and bottom faces of a hollow cuboid or a thick-walled cube. 4. The lines connecting the squares represent the vertical edges of the solid, giving it thickness. 5. Since the squares are concentric, the shape is a cube with a hollow interior, i.e., a cube shell with uniform thickness. 6. To model this, consider the outer square as the outer face of the cube and the inner square as the inner face, both extruded vertically. 7. The thickness is the distance between the outer and inner squares, and the height is the distance between the top and bottom squares. 8. The 3D shape is a hollow cube (a cube shell) with thickness equal to the difference in side lengths of the outer and inner squares. 9. The volume of the solid cube shell is given by the volume of the outer cube minus the volume of the inner cube: $$V = a^3 - b^3$$ where $a$ is the side length of the outer square and $b$ is the side length of the inner square. 10. This shape can be visualized as a cube with a smaller cube removed from its center, leaving a solid shell with thickness. Final answer: The 3D shape is a hollow cube (cube shell) with thickness equal to the difference between the outer and inner square side lengths, formed by extruding the two concentric squares vertically and connecting their edges.