easy second level for my tortoise?

[byviolet]

So I keep my tortoise in a huuuuge aquarium, but I want to see if I can give him a little more room (plus I think it would look cool) by adding a second story. Imagine your typical rectangular aquarium. I want to put the second level right in the middle of that rectangle, with ramps leading down both sides. Is there an easy way I can do this? I was thinking wood but I worry that it would quickly mold and rot because I keep the aquarium very humid. Thoughts?

 

[wellington]

Paint or seal the wood. You could also use plexi glass/acrylic

 

[byviolet]

Would something like using modelling clay or cement be easier?

 

[johnsonnboswell]

Plexiglass. Put treads on it.