It's a ninja sword, like the ones you may see in many movies or comics.
It takes less than five minutes and it's not expensive, provided you have the items you need...
Step 1: The items
1 wooden broomstick;
1 hard disk (you have to dismantle an old one and pick up a single disk);
1 foam knob from a bike's handlebar;
1 salad bowl stolen from Barbie's kitchen;
some rubber bands.