Elation actually makes a battery powered LED fixture called the Event Panel. Should be exactly what you are looking for.
With regards as to how to make your own battery powered LEDs, it is something that shouldn't be discussed on open forum since someone can be seriously hurt or even worse, killed. If your not sure how to do it, don't do it. Not worth playing with your and others lives and well being. Even if you get an electrician to wire it, it still won't be UL, ETL, and/or CE approved. If an issue arises, like a fire or someone getting hurt, the ones who use the fixture and those responsible for its construction would have numerous law suits filed against them and quite possibly criminal charges.