Measure the width and height of your toddler bed. It should be roughly 54 inches wide and 20 to 28 inches high off the floor, depending on whether the mattress is laid on wood planks or a foundation--formerly known as a box spring.
Purchase a sheet of 4-by-8-foot plywood or particle board and two beams of 1-by-4-inch lumber. These will form the headboard and the legs. In addition, purchase enough yards of fabric of your liking to cover the headboard.
Put on safety glasses. Mark and cut the plywood and particle board with a circular saw to fit the width and height of your toddler's bed. The headboard should generally be at least 56 inches wide and 30 to 36 inches high.
Cut the 1-by-4-inch lumber beams to fit the total height of the bed and the headboard; these legs will range between 42 to 48 inches long.
Sand the plywood or particle board and legs until smooth with sandpaper.
Wrap the headboard and legs in fabric and staple the fabric to the headboard and legs. Then, fasten the legs to the headboard with a screw gun and stainless steel screws. Put the screw heads and staples on the backside of the headboard, where is will be concealed by the wall it sits against.
Pull the toddler bed away from the wall to expose the head. Measure the bed to find where the retaining bolt holes are already drilled in the frame. Mark the same measurement on the headboard or legs and drill holes to insert carriage bolts.
Align the newly drilled holes in the custom headboard with the existing holes in the bed frame. Insert the carriage bolts into the holes and tighten with a wrench.