2. Draw a grid on top of the foam with a marker (cross sections of the lines will determine the exact button location). Cut the foam following the lines using a razor or sharp knife at least one half of the depth of the foam (two inches when using four-inch-thick foam) and should be cut down the sides of the foam at a depth of at least one inch to allow the material to be tucked or tufted (figure A). Cuts do not have to be continuous and can be stopped just short of the area where the buttons will be placed.3. Mark the same grid pattern on the plywood piece to match the spot where the button threads will come through the plywood to be anchored. Use a drill with a small bit (a nail and hammer will also work) to make holes in the plywood at each button location.
4. Cut material to size, allowing an extra one to two inches of material for EACH channel cut into the foam, both vertically and horizontally, for fabric tucking. Cover buttons according to the instructions. Thread button back with ample amount of upholstery thread (at least 24 inches doubled through the eye of the button back). The longer length of thread will ensure easier tightening and anchoring of buttons.
5. Place material right side up over the grid-marked foam piece. Keeping the fabric taut and aligned (take extra care if using a patterned material), wedge equal amounts of material into each channel of the foam both vertically and horizontally. Use an upholstering needle to pull button thread through foam at designated button location, and on through the hole in the plywood. Note: Spray adhesive can be used to attach plywood and foam for ease in anchoring buttons, but is not necessary. Repeat this step until all buttons have been placed at grid locations.