Step 1: Materials
1. 2 pieces of paper (I used computer paper)
2. Tape (I guess liquid glue would work too, but tape is easier to use)
3. 4 pennies (Optional, for added weight)
4. A pencil (Not exactly necessary, it just helped me to form the handle and the ring)
5. Scissors (If you aren't very good at ripping paper, or want a cleaner looking kunai. I personally just rip my paper.)
Step 2: Blade and Sheath
2. Take one of the fourths and fold it in half along the line shown in the third picture
3. Fold the paper as shown in the fourth picture, using the middle line as a guide. It should look like the fifth picture.
4. Fold along the line in the sixth picture, again using the middle line as a guide. It should look like the seventh picture.
5. Fold along the line shown in the seventh picture(Yet again, using the middle line to help you. Don't you just love the middle line?). It should look like the eighth picture.
6. Make 3 more of these. In the end you should have four.
7. Put two of the triangles together as shown in the tenth picture. It should look like the eleventh picture. Tape together.
8. Make another of these using the other two triangles. You should now have two. One of these, you can set aside. It will be used as the sheath for the kunai. The other will be used for the blade.
Step 3: Kunai Handle and Ring
2. Take two of the fourths and lay them horizontally. Tape. You can also add a third fourth onto the middle of the first two for added strength.
3. Use the pencil(If you decided to use one) to roll the paper into a tube. Tape the tube. It should look like the fourth picture. This will be your handle.
4. Take the other fourth and lay it horizontally. Roll it into a smaller tube. Tape. It should look like the fifth picture. Flatten the tube to look like the sixth picture.
5. Trim the flattened tube to make a ring the size of your choosing. It should look like the seventh picture.
Step 4: Forming the Kunai
1. If you decided to use pennies, put the pennies into the blade(Second picture. Oh look, my hand!)
2. Insert the tube into the blade
3. Flatten the end part of the handle
4. Put the ring onto the flattened part of the handle(Sorry, no picture)
5. Loop the flattened part of the handle through the ring. Tape. It should now look like the fifth picture
6. Fold the corner of the blade as shown in the sixth picture
7. Do the same for the other corner. Tape. It should look like the seventh picture.
8. Insert the kunai into the sheath. If you were able to follow this entire instructable, you now have a finished kunai and sheath. Good job!