Welcome to the forum @Heimegger! Classic Rock & BM... That's a range we have a wide range of tastes here - we even have another forum here for other music.
Good to have you aboard.
You could get a black tactical vest and a silver spray paint can. He sometimes wears gloves with really long fingers... For that some black gardening gloves with hair clips glued to the end?
You could spray paint them black too.
You could also get some spikes like these: https://www.ebay.co.uk/i/181249138788
We all see it at gigs and shows, a lot of us will join in, but where does the "horns up" hand gesture (synonymous with Metal) come from?
What does it mean really mean when we do it?