The butterfly knife, or balisong as it's known in the original Filipino, is a fast-moving, self-contained and impressive-looking weapon. It's also very dangerous in an untrained hand--to others as well as to the user. For that reason, it's a good idea to practice your butterfly knife tricks with a balisong made of paper instead of metal. It's a quick project and it may save you a finger.
Position one sheet of paper with the long edge facing you. Spread glue on the left half of the page. If you're using a bottle of glue, scrape the glue with a piece of scrap cardboard to spread it thinly and evenly across the entire page.
Fold the right edge of the paper to the left edge and score the fold by rubbing your thumbnail along the fold. Wait a few minutes for the glue to dry.
Spread glue on the left half of the folded paper again. As before, use scrap cardboard to thin and even out bottled glue.
Fold the right edge of the page to the left edge again and score the paper.
Repeat this same process with the other sheet of paper. Set one aside to dry for about 10 minutes; this will become the blade.
Take one of the sheets of paper and fold in half once more, then score it with your thumb. Don't use glue on the page this time.
Open the paper again and fold the edges into the centre crease. Score it with your thumb again.
Cut the paper in half to form the two halves of the handle. Leave these pieces to dry for about 10 minutes.
Take the other sheet of paper. Place a quarter in the centre of the paper, about 1/4-inch above the bottom of the paper. Trace the bottom half of the quarter.
Draw a pair of tabs jutting out from either side of the semicircle. Make them rounded, about 3/4-inch tall and 1/4-inch from the edge of the paper. This forms the base of the knife blade.
Draw a knife blade leading up from the knife base. You can make the blade as simple or as ornate as you like. A butterfly knife typically has a simple, teardrop-shaped blade, with a dull side and a sharpened edge. Remember that you will need to cut this piece out.
Cut the blade out of the piece of paper.
Take a handle piece and cut an angled notch into the top, at the folded corner. This will form a slight V-shape in the top of the handle. Repeat with the other half of the handle.
Put the blade into the handle. Slide one handle piece around the blade, sticking the tab into one of the notches. Slip the other handle onto the other side of the blade in the same position.
Pierce the centre of the left tab through both parts of the handle with a thumbtack. Push a piece of rubber (such as a pencil eraser) over the end of the tack. Open and close this half of the handle a few times to widen the hole slightly. Repeat with the other tack and tab.
Open and close the knife completely a few times until the handles open and close freely. You may need to loosen the rubber stoppers slightly.
If you're making the blade out of a thicker card stock or paper, skip the assembly part and cut an 8 1/2-inch by 11-inch piece of cardboard into quarters. You can find simple butterfly knife tricks on the web.
Take care not to stab yourself in the thumb with the thumbtack while assembling the model.