Canon has a new macro lens that has two built-in LED lights. It's a rather novel idea, and you can turn on one or both lights.
It's a 28mm lens intended for its EOS M mirrorless cameras, which converts to a full-frame equivalent of 45mm. It's a true macro lens with 1:1 reproduction.
I have written an article here:http://photographytoday.net/?q=news/can ... s-m-system
There is a promotional video that shows how it works.
I would expect that it contains plastic lens elements, because it weighs just 4.6 ounces (130 grams).
It makes me want to try it.