Boushh helmet dimensions?

Ive persuaded my wife to start a Boushh costume \o/ horray. All I need now is a Thermal Detonator, her staff or a Wookiee on a chain She wants to sculpt the helmet herself. Could someone please tell me the dimensions for a Boushh helmet? Height, width... any obscure measurements we might need etc. Id really appreciate it.

Of course if someone knows the original prop dimensions that would be fantastic but the accepted standard would be a great start for her sculpt.

Many Thanks