How to Make a Paper Kunai Knife

Folding the Blade

Get two square pieces of paper, preferably black construction paper. One should be bigger than the other, to be used for the handle. This can be found at any craft store. Gather the rest of your materials. These include some tape, scissors (to cut the paper into squares), and, optionally, a small, heavy object, like a penny.

Holding the smaller square, fold one corner to the opposite side. It should now look like a triangle.

Fold a crease halfway through the paper. It should now look like a smaller triangle.

Unfold the paper. Now, it's a triangle with a crease.

Take one of the short sides of the triangle (not the long one) and fold the edge to the middle. The edge of the side you're folding should line up with the crease. Flatten the fold down.

Keep folding repeatedly until you can't fold it anymore. Then tuck the extra paper inside the kunai.

Squish the paper from top to bottom so that it creates a kunai shape (grasp by edges and press). This step isn't that necessary. It just makes a flatter kunai.

Making the Handle

Take the larger square paper and roll it into a thin tube for the handle. Tape it.

Insert the tube into the hole. You may need to open the blade a bit to allow the tube to fit.

Wrap your hand around the section of the tube next to the blade. Make sure there's enough of the tube that you can hold it. The extra bit, sticking out from your hand, should be flattened. Optionally, before flattening the extra length of the tube, cut a chopstick to the length of the handle and stick it inside to improve the stiffness of the handle.

Use a series of folds and reverse folds on the flat side of the tube to create a circle. You'll be making 90 degree folds in the flattened tube, in a counter-clockwise fashion.

Tape the circle so that it stays. One piece of tape connecting the end of the tube to the unflattened section should do it.

Tape or staple the tube into the back of the kunai (where the hole is). Make sure the handle is secure. Use extra tape here if necessary.

Finish the Kunai Knife

Take something heavy and put it inside the knife so that it can fly better. Pennies work well and are cheap. This step is optional.

Seal the kunai with thick tape so that the heavy object doesn't come flying out when you throw it. Place tape over where the blade and handle meet, enough of it to seal and secure the heavy object in the blade.

Finished. You've now got your very own paper kunai knife. Avoid throwing it at people as you could injure someone.