Is there a way to make "block helmet" like the pumpkin block.

So you can wear and maybe set a custom texture with the eyes, mouth, etc. transparent but it's not very important.

 

I think there is no way to do this so please add this.

This is something I am interested in as well. Something I would also like is being able to set an item or block so that if it is on your head, an Enderman won't attack you if you look at one, also like a pumpkin. That way we can have that functionality on our custom block helmet. (And we could have blocks that go on your head that don't do this.)

Subclass anyone?

no, you could have any block on your head actually, if you can get it into the slot. the problem is that the pumpkin overlay to your screen is rendered in base classes. endermen behavior is also in base classes.