Step 2: Put the materials to work...
First of all I don't want anyone stabbing people with this pencil. That is not the use it was intended for and a non-butterfly pencil would be much more effective in causing pain or injury.
The contraption will be built in a series of three steps: fastening the pencil and preparing the hinge, making the handle, and making the hinge which completes the product.
First, gather your pencil, tape and plastic. Now place the pencil in between the plastic pieces and tape it there. It should look like this: