Daft Punk helmet from baseball helmet

Hi everyone!

So I read and reread many threads and have a few questions about a building a Daft Punk helmet for hallowe'en.

Now I know all of you are probably saying "pfffft not another one"

But mine will be different and you will see once it is done. It is more of a Daft Punk Inspired helmet.

Anyways, the helmet will be Thomas's helmet which will be started from a low profile rawlings baseball helmet. But will have a few changes to it from the original ones.

My question is:

After applying the bondo onto the helmet, to strengthen the inside, do I use bondo again? spray foam? or nothing since the baseball helmet is basically still there.

Thanks! And I will post photos of progress.

Antoine