Thanks for the kind words

I polished a little circle on the inside of the enclosure lid directly above the light bulb, at the moment I'm playing it without a sheild at all.
I used the lid of a Stelvin Closure wine bottle cap as a light sheild while I dialed it in. It fits perfectly and is quite shiny on the inside. I must admit though, I'm not sure how much of a sonic difference it actually makes to have a light sheild. I suspect the angle, values and proximity of the ldrs is more likely to have an effect... I'm going to do further experimenting.