Which woods are safe?

[Shurrim]

I love to make cozies for my piggy, but I fell the need to make him some toys and I was wondering which woods are safe for them, so they can chew on ..
I've heard about maple, balsa.. safe? anything else?
Also, how to color them? Food coloring stuff.. won't it bleed out?
And what kind of rope should I use?

 

[lissie]

aspen, kiln-dried pine

 

[Nicolene]

I think I read ( and I may be wrong) that you can use any fruit tree wood that doesn't have a fruit with a pit (like peaches). I bought some "organic" apple twig ones from a PetFoodExpress and my pigs couldn't care less, so don't spend too much on it, make sure they enjoy chewing on wood. My pigs don't like any toys (I've tried so many things). Mine only appreciate tunnels (cardboard, not plastic) and comfy hideys and I like to build towel tunnels in the winter that they snuggle in ALL DAY.