I bought these for my kids and they are great but proximity to balloons have me an idea. The length of lace (in a loop) is about 80cm and they light up the entire length. On this design there was nowhere to hide the main box bit but I can see me using these on future designs to add a little light (they come in a range of colours and cost between £1 and £2 depending on whether you want it from the uk or want to wait and get it form china.
Good fun