This concept design marries both lens cap and lens hood into a single device, opened with a simple twist.
Designed for the 2011 Spark Awards, the Flower marries two things you probably already have on the front of your lens — the lens cap and the lens hood. This concept was put together by Rhie Hyi Joong & Lee Sang Hwa, and would make use of a semi-rigid material for the individual blades around the cap. A threaded ring at the base of the Flower could be twisted, opening or closing the iris as required.
If this thing were real, not only could you use it to protect your lens when closed and stop flares when open, but I bet you could do some interesting photography with it partly retracted, as a second aperture.
I could definitely imagine some problems with it, though. Preventing light leaks when it's in hood mode would be one, and I could easily see detritus getting caught in the hood blades and being transferred onto the glass.
I'd still totally buy one — if only they were real.