Measure and trim the 2-by-2-inch baluster to 24 inches long. Lay the trimmed baluster on a flat surface. Attach screws to the center of the board from end to end about 5 inches apart. Do not drive the screws completely through the baluster. Once installed, this board will serve as the gate stop.
Position yourself on the non-swinging side of the gate. Close the gate. Align the front of the gate to the front of the opening-side gate post. Place the gate stop vertically on the opening-side gate post near the vertical center of the gate. Precise positioning is not necessary.
Align the edge of the gate stop with the vertical stile of the gate frame. Screw the gate stop to the gate post.
Trim a piece of 2-by-2-inch baluster to 6 inches long to make the pivoting latch handle. Measure and mark the center of the trimmed baluster. Drill a 3/16-inch hole completely through the latch handle. Insert the lag screw into the hole in the latch handle. Place two washers onto the threaded end of the lag screw. The washers allow the latch handle to turn once the latch is installed.
Mark the post at the height you intend to install the latch. Test fit the latch handle on the post. When the handle is turned vertically, it must not impede the opening gate. When the handle is turned horizontally, it must prevent the gate from opening. When the latch handle is in proper position, tap the head of the lag screw with a hammer to mark its position on the post. Remove the latch handle.
Drill a pilot hole about 1 inch deep through the indented mark on the gate post, using a 1/8-inch drill bit. Place the tip of the lag screw attached to the latch handle into the pilot hole. Tighten the lag screw with a socket wrench.