Hardware Cloth -- Wire or Plastic?

[dot n'dave]

I wouldn't suggest anything but the metal, unless they were TOTALLY secure at night.
And as for not having predators, you will if you have chickens.

I never saw raccoons until we got our chickens and they killed all but two last year.
To save some money is not worth the time you wasted raising your flock and then losing them.

Good luck with the construction!