How can I safely create a sort of climbing shelf for my toad out of some wood I found in the shed?

[jack022]

I've read that treated wood should be sealed, but I'm not sure what to use. I want to make something like an elevated shelf for my toad to sit on. For some reason, despite being an American/Fowler's Toad, she really loves to climb. What would you use?

 

[Woody Stover]

I've read that treated wood should be sealed, but I'm not sure what to use. I want to make something like an elevated shelf for my toad to sit on. For some reason, despite being an American/Fowler's Toad, she really loves to climb. What would you use?

I would be concerned that treated wood might contain chemicals harmful to my small non-furry friend. I would instead locate some rot-resistant wood such as Black Cherry, Red Elm or Sasafrass, and build the toadstool out of that.