Measure the width between the hall walls and decide on a height for the gate. If the gate is intended for a toddler, only his head should be taller than the gate.
Cut four pieces of wood as long as the measured width minus 5 inches. These four pieces of wood will form the gate's top and bottom frame.
Cut two additional pieces for each of the gate's side posts. Cut two 4-inch-thick pieces of wood to the desired height to create the side posts. Place the side posts aside.
Run glue between the two top frame boards. Then sandwich the boards together. Repeat the process to glue the two bottom frame boards together.
Punch 3/4-inch nails into the corner of the top frame boards with a nail gun and into the bottom frame boards to ensure they stay connected. Add extra nails to the length of the board sets every six inches.
Position the glued-bottom frame board on its side. Use a drill with a 3/4-inch spade bit to create baluster holes every three inches in the center of the bottom frame board.
Drill baluster holes into the glued-top frame board with an 11/16-inch spade bit every three inches.
Bead wood glue to the tops and bottoms of each baluster. Then push each baluster into the holes in the top and bottom frame boards.
Drive a nail through the sides of each frame into each baluster with a nail gun.
Drill holes into the left and right corner of the bottom board with an electric drill. Twist the screw on each caster into the hole. The casters, or wheels, will allow the unlocked gate to open and close.
Dry fit the side post along the wall. Trace the top of the post to indicate its placement, then remove it.
Place the longest side of one L-bracket flat against the wall near the top of the post mark. Mark the bracket's screw holes with a pen. Remove the bracket and create pilot holes through the screw marks with an electric drill. Insert drywall anchors into the pilot holes. Then reposition the L-bracket against the wall and drive screws through it and into the inserted drywall anchors. Repeat the process to install another L-bracket 3 to 4 inches from the floor.
Butt the post against the free-side of the L-bracket. Screw the L-bracket into the side post with the electric drill.
Stand the gate up next to the wall. Open and close the gate by hand to make sure the gate placement allows it to close flush with the side post.
Draw a line to indicate the height of the top and bottom frame boards on the wall. Remove the gate. Place a hinge flat against the wall just below the top frame board line. Mark the hinge screw holes. Remove the hinge and drill pilot holes. Insert anchors into each hole, replace the hinge and screw it into place. Repeat the process to screw another hinge just below the bottom frame board line. Screw the other side of each hinge into side of the top and bottom frame boards.
Screw the "lock" portion of the gate latch lock into the side post. Screw the "latch" portion of the gate latch lock into the gate post. You now have a gate for the hallway.