3. (6 points) As shown in the figure, it is a $4 \times 4$ grid, with 3 small squares shaded. If one more small square is shaded to make the grid a symmetrical figure, then there are $\qquad$ different ways to do this.
【Analysis】According to the characteristics of axisymmetric figures, the distance from the symmetric points to the axis of symmetry is equal, and the line connecting the symmetric points is perpendicular to the axis of symmetry. By drawing the key symmetric points of the left figure on the right side of the axis of symmetry and connecting them in sequence, we can achieve the desired result.

【Solution】
For (1) and (2), both can be colored, so there are 2 ways;
Therefore, the answer is: 2.