From what I have read, IT decryption software can decode most passwords in under a minute. The best ones are those that use keyboard top line symbols as well!
Cheese grater, chain mail armour, colander, sieve, chain - all made of steel and holey!
(A scientific reply would be carbon titanium, with holes in it to make it lighter for use in aerial vehicles (planes, space shuttles, etc.)
Bang go the "Gold coin entry" venues - and the "Buy and Sell" sites on Marketplace , Bunnings' (and others') barbeques.. and busking.
I am sure most people could come up with so many more places where coins used to reign supreme (vending machines being one)!
Of course, in the journey of one...