If you're not handy, don't have the tools to cut them yourself, or aren't able to find untreated 2X4s near you, I'd recommend buying some from The Parrot Asylum. It's the only place I've found that sells them; plus they have fantastic service and prices!
Have I already posted a picture of Max in the fridge? I can't remember, so this may be a repeat! I like to watch parrot videos on youtube in my spare time, and I found one of a timneh dancing in the fridge. Of course I had to try this with Max! She does love it in the fridge, but as we don't want to cool the house down so inefficiently, she doesn't get to go in here very often (we always leave the door open, of course!)
The next youtube video I am going to try to emulate is one I saw of a severe macaw that pretended to be a bowling ball and ran into 10 empty water bottles that had been set up like bowling pins, knocking them all down. I am on the lookout for a cheap set of plastic bowling pins, like what kids play with! Of course, when I video this, it will go on the blog!