Hi Graham,
I made a dew/light shield for my LB12".
I used a product called H.I.P.S.
High Impact Polystyrene Sheet
It comes in a 1.37mX 60cmX 0.75mm.
It is very flexible, strong, light and easy to cut with a pair of sharp scissors.
It has worked very well. Cost? was about $15 a sheet.
I purchased it through a plastics supplier here in Sydney, but I'm sure a similar place in Brisbane should have it.