Slipknot is right.

Metal screen probably aren't the best for you, but they are a clean metal, is that the right word? Lets just say it's much better for you than pop can material.

For glass pieces though, they do sell small Jax shaped or star shaped glass screens. I use them in my bong, bubbler, and spoon.

The only one I have a metal screen is, is in my steamroller, but it's made from stone.