Poking holes in silicone won't work. It's so flexible that the holes will basically close themselves back up. You would have to drill holes to actually remove some material.
Basically, any heat resistant material could make a manifold. The sky is the limit. It's just a matter of making a million little holes in it. (The braided mesh comes with those million holes already, so it is pretty convenient. ) If you are batch sparging, it's' pretty simple. If you are fly sparging, you'll want to look at some common configurations to make sure your design creates uniform flow.