Well, I guess the whole point of the exercise is working with the candlelight by itself.
You could become more experimental - by wrapping tinfoil around some pieces of cardboard, you could try reflecting some of that light back onto the lid, create a rim light around it so to speak. Or even use a few pieces. See how much light you can get back onto the back rim of the actual candle holder, from the top or top left.
You could try covering the surface with black cloth, see how it works without the reflections.
And/or secure the lid with some putty, so you could move that support out of frame. Hard to see what it is...
Anyway, you're experimenting and playing right? It works as it is. But there are many things which you can try to do differently, or additionally.
I think even waiting till the candle has burned itself to the point where the flame is inside the container, will open worlds of possibilities.
.
