Long-lasting safe wood for runs?

Hiya,
I was wondering whats a good, long lasting wood that you would suggest to make a run? I want this run to last. Or is there a preservative that wont harm? Inexpensive is also great.

Thanks!

We used pine, as it's not in shaving form we figured it would be ok. We stained it with this http://www.cuprinol.co.uk/products/timbercare_overview.jsp as it was the only one we could find that said safe to use around pets. In terms of protective power to the wood, it's the lowest end of the scale as you'd expect from something pet friendly. We made the wire of the run cover it from the inside, so the only bits of wood they can chew are in the hutch, Honey has done this a little and is still alive so far...

:wave: I'm glad you asked this question as I was thinking about this too. I want to make a run for our two buns but don't want to use any materials that may harm them.