I cut myself some stiff plastic lamination folders (the non-sticky side) and used them to cover the screening to keep humidity in. Seems not to lose much of the light, if any. Humidity is MUCH higher, seems like a nice, cheap fix.
Are you 110% positive and sure that plastic doesn't contain anything noxious to the frogs, or perhaps an endocrine disruptor or a hazardous petroleum by product?
Much better than saran wrap Brian ! Probably won't warp either.
Lots of clear plastic sheeting can be obtained at Staples, Office Max and even craft stores like Michaels.
I would not put a light / heat on it or near it and probably would not want water on it or dripping from it - just to err on the side of caution as it's definitely non-food grade plastic.
Good find though.
Actually, it is food safe! One of the reasons it occured to me that it might work well.
As for light, I use CF lighting and LED's would be fine if the standard fixture, it doesn't even get hot. A regular bulb would likely NOT be a good idea. I have seen people melt the plastic of the terrarium itself!
I cut out glass to fit over exo/zoomed screen. You can adj as needed (nudge it a bit) to control humidity for breeding and general climate manipulation. Glass is cheap and has no surprises w heat and cleans up easy.
My humidity must be near 99% as the glass stays a bit foggy in spots. I have the mechanical Exo gauges, but those don't really read the full range so hard to tell. I'll have to dig up the full range digital one some time.