Has anyone used the wire hardware cloth for their grille ?
I'm wondering if it's going to rattle or buzz.
Am I supposed to PL the wire mesh to the legs on the window braces that lead to the Phase plug (center of the baffle) ?
Yes secure everything, leave nothing to chance that could vibrate against eachother. Just be sure it doesn't expand too much to hit the cone/surround, spread a thin coat and use heavyduty staples as needed to hold the mesh/grille tight to the legs.
In the front of the horn throat, I've seen some members use a foam phase plug. Can this be any shape and size ?
The most recent versions all use a specified phase plug, if you're unsure of this update your plans.