guinea pigs bedding
Wood chips are a bad idea. Most have wood oils that are toxic to guinea pigs. Even lighter woods are bad, as they are rough and hard and can hurt guinea pig feet. The best bedding is plain black-and-white newspaper. Line the cage with that.
Next add a pile of hay - you can never give too much hay. Guinea pigs do not overeat hay. If they have leftovers, they like to sleep in it. And the newspaper under everything makes it easy to clean upthe cage,just roll it up and throw it away. Thick newspaper in the hutches holds the heat in winter so the guinea pigs arc kept warm.