Purchase padding. You have the option of buying custom helmet pads or buying foam and cutting it to shape. OE Tech offers a seven-piece memory foam pad set for use in replica tactical helmets, and Atlanco has a foam-construction single-piece circular foam pad made for Kevlar helmets. You could also visit the bicycle department of any store and purchase foam helmet pads designed for bicycle helmets.
Remove the liner from your helmet. Wash the inside of your helmet with soap and water. Let it dry. If using helmet pads, remove the adhesive strip from the pads and place them in the center of your helmet. If you're using bicycle pads, place the pads in a circle around the center of helmet, leaving a 2-inch circle open in the center.
Cut the foam in a circle large enough to cover the inside of the helmet an inch above the face opening. Cut a line through the foam from the outer edge to the center. Place strips of double-sided tape along the inside of the helmet, spaced ½-inch apart.
Place the foam inside the helmet. Begin at the center of the face opening, with the cut end of the foam facing the back of the helmet. Press the foam into place, first from the center of the face opening to the center of the helmet. After that, press the left half of the foam into the helmet, then the right. Prevent the foam from bunching as you place it.
Replace the helmet liner.
