3. (6 points) As shown in the figure, it is a geometric body composed of 26 identical small cubes, with its bottom layer consisting of $5 \times 4$ small cubes. If the entire outer surface (including the bottom) is painted red, then when this geometric body is disassembled, the number of small cubes that have 3 red faces is $\qquad$ pieces.
【Answer】Solution: According to the problem, we know:
The first layer has 4 corners that meet the condition.
The 4 corners of the second layer are 4 red faces, removing all corner pieces, the rest meet the condition.
They are $3+2+3+2=10$ (pieces)
In total, $10+4=14$ (pieces);
Therefore, the answer is: 14