A few years back I was having problems lighting a scene. It wasn't a problem with the back light or the key but with the tiny amounts of fill light I needed, just a few footcandles. As time went by the problem became worse as cameras became more sensitive.
Quite often after putting trace and gels on a light more light was coming out of the back of the light than the front.
So as DOP are want to do in their down tie is play around with building a light with some LEDs off ebay.
I was quite excited with the result and thought I wonder if any engineering company would help. In the past engineering companies would not talk to you unless you wanted to make 100,000 units. So it was just for interested I phoned a company just outside London in Harlow. To my surprise that invited me to meet with them, at the meeting invited in their designer and together came up for this soft LED light.
As a DOP I wanted a light without the multiple points of light, running of a generic 12 volts DC, went up in stops and was well made in metal, with snoot and egg crate and no light leak.
So here it is
I hope this is of interest, more info http://www.softylite.com