In making paper knives and swords, the resulting models hold up better if the paper is harder than normal printer paper. Although you can use heavier card stock paper for paper knife and sword projects, you can also harden the paper yourself. Hardening your own paper is also a great way to use scrap paper that would otherwise be thrown away. Start your paper stiffening session at least a day before your paper knife or sword-making session to give it time to dry completely.
Cover your work space with a plastic dust sheet to protect the table top from damage.
Place a sheet of scrap paper on the work space.
Squeeze a generous amount of white craft glue onto the sheet of scrap paper. Leave a border of about ¼ inch around the perimeter of the paper.
Spread the glue into an even coat covering the paper with a foam craft brush. Brush the glue just to the edge of the paper. If the glue is too thick to spread, dip the tip of the brush into water and squeeze out the excess before spreading. This will thin the glue a little.
Place a second sheet of scrap paper of the same size directly over the glued sheet. Bow the sheet a little and make contact with the glued sheet in the middle first. Let the unglued paper lay lightly onto the glued one. With the side of your hand, start in the middle of the unglued paper and smooth it toward the edges to remove air bubbles between the sheets. Avoid getting glue on the top sheet.
Pick up the glued sheets carefully and place them on a clean spot on the plastic dust sheet. Cover them with a sheet of cling film and place one or two heavy books on top to press them flat. The books must cover all of the paper. Leave the books on top of the stack for at least 24 hours until the glue is completely dry. Use the stiffened paper in your craft projects.
Add another one or two layers of glue and sheets of paper to the stack to make extremely hard paper.