Measure and cut eight 4-inch long pieces of 2-by-4 board using a circular saw. Smooth the cut edges with sandpaper.
Stack two board pieces together to form a block that is 4 inches in depth, width and height. Drill 1/8-inch pilot holes into the blocks, one at each corner and insert screws into the pilot holes. Screw the blocks together with 3-inch wood screws, using the power screwdriver.
Center a round rubber furniture foot pad on the block. Secure it to the block with a 1-inch wood screw, driven through the center of the pad.
Repeat the previous two steps to make three more blocks. Place the blocks underneath the legs of the sofa to raise the sofa 4 inches. The sofa legs will fit within the round rubber foot pads.