Measure the length along the base for each wall. Write these figures down.
Cut baseboard pieces to match the required lengths.
Use a miter box and saw to cut 45-degree angles on the ends of each baseboard. Place the baseboard in the miter box and line up the end next to either the right or left 45-degree angle slots. Use the miter saw to cut the baseboard ends.
Arrange the 1/2-inch spacers on the floor, between the carpet and wall, spaced about two feet apart. Place the baseboard onto these spacers.
Hammer nails into the baseboard to attach it to the wall. Continue around the room, attaching the baseboards to the walls.
Remove the spacers carefully with a screwdriver and needle-nose pliers.