Intro: Button Disc Saw
here is the demosntration video
to make this simple toy you will need button ( biggest you can find with two or four holes ) and sting ( soft but stiff plus it needs to fit the hole about 60cm more or less ) thats it. pull the string thaugh the two holes if theres four do it like with two.
You can allso make handles for more comfortable use from small hose or two sticks like pens.
starting it could be a little tricky you need to spin it a little with no tension then start pulling it, its hard to explain you coul see it in the video.
we used it for duels with weak string and sharp buttons, the goal is to cut you oponents string.