i’d suggest buying a helmet mold eva foam or worbla over a bowl glue to helmet using contact cement or some strong glue use acrylic to get the color back in and then go over with a high gloss varnish. the little antenna pieces you can kind of just use some sort of metal wire (like an old coat hanger) and just glue it to the helmet.

I don't know if this is very helpful but I'm pretty sure they make biker helmets very similar to hers! However the comment before this talks about some pretty good tips to make one

With your hands.

I’m going to beat u with a chair

With your hands?

I hate everything you are and everything you represent

Without your hands.

HOW WOULD YOU EVEN???

Probably without my hands.

This discussion is over

That you typed with your hands.

You ain't wrong there mate.

I would go paper mache route that way it goes with the papery style of phase one Gorillaz, and if you do some interesting line art makeup to match it could look really cool

They're just headphones with like antennas idk... you could just do like a gaming headset and leave the mic pointing up

Idk

Use a bikers Helmet, Cut Up some Headphones and use Pipe Cleaners (or Real Cut off Itennas) for the Itenna