All you need is an old computer fan, sandpaper and a source of direct current.
1.Make circle of sandpaper (diameter off movable part fan).
2.Secure the circle of sandpaper for fan.
3.Conect power sorce to fan.
Do not touch the sandpaper by hand when the device is active, Connect the correct voltage (usually 12 volts DC).
Improvised Electric Knife/Tool sharpener in action