What about gelatin shapes covering the cake? Possibly even en-cage it with small battery operated lights nestled inside to make it glow? Not sure I am explaining myself well. Good luck whatever you decide!
Great idea ladyhawke917. I hadn't thought of either of your ideas, lights or gelatin shapes. Maybe that's something I can experiment with when I have more time. I ended up doing a splatterpaint on white 2 tier using those neon colors. She loved it.