The Queen has been talking about her Coronation. If any of you should, by chance, find yourselves being crowned in the future, Her Majesty's advice would be "Don't look down". The crown is very heavy and you might break your neck.
So bear that in mind, it's apparently a lot heavier than a climbing helmet.
Strikes me, we could sell the antique crown we have and replace it with a new, lighter, carbon composite version at some advantage to the exchequer. I garner the likes of Kim Jong-un and Jacob Zuma are constantly scanning Ebay for second hand crowns.