If you've never seen the Flash Disc, it's basically a small, foldable softbox that fits directly on top of your speedlight. Because of its collapsible design, the 12" Flash Disc quickly folds up and easily fits in your camera bag, backpack, travel luggage, and even your back pocket.
Lee and I designed this light modifier years ago to help us quickly light food, portraits, rings, and detail shots at weddings, but over the years we have found it useful for so many more applications. The design allows it to fit on top of all the major brands' speedlights and can be used both on-camera and off-camera (although we recommend using it off camera the most).
Below are a view videos we have produced showing how versatile the Flash Disc can be in a number of situations, and while it was never meant to completely replace the look of a large softbox or umbrella, the Flash Disc balances the convenience of having a small light modifier with you at all time while still giving you a softer light than a barebulb flash.
Shooting Beauty With The Flash Disc
How to Shoot A Beer Bottle With the Flash Disc