I can give you a couple of tips to playing metal.
The first tip, after striking the metal, bring the mallet off the metal to create maximum resonance.
The second tip, make sure the metal is freely suspended and freely allowed to vibrate. This will create the maximum sustain the metal can give.
The third tip, make sure you strike the metal with something that won't corrode the metal itself, and don't let the metal corrode by induction to air or water either. This is a great way to ruin your experience playing metal.
The fourth tip, using a parabolic dish behind the metal acts as an acoustic resonator and will greatly amplify the sound of you playing metal.
That should be a start for you. Let me know if that helps.
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Seriously, the worst thing you can do is sweat it. There's so many ways to play it, you could play with or without a pick, play roots, double the guitars, or grab a fretless off the rack and pull off your best Sean Malone imitation. The options for you are endless depending on the band and the options of which you're given.