Justin, I think it may be easier to cut some glass to size (be sure to sand off the edges - very sharp otherwise!), put the film onto this with some low-tack glue or do it the "Ole Tjugen way" - use some jam or marmalade as glue.

I think it is the high amount of sugar that is the active ingredient in this. So, maybe just water with a lot of sugar works, too? I may be wrong...