Hex Tank Screen

[LilyPad]

I have a 35 gal hex tank that was formerly an aquarium. I think I am going to want to move my tree frog into that tank. I think she would love the height of it and then I could add another frog in there. Also I have a really nice stand for it (right now the frog tank is sitting on my kids' table!) I don't have a suitable cover for it though. Where could I find (or how could I make) a screen to put on the top of it? How difficult would it be to clean, I had a terrible time cleaning it out when fish were in it!