Aus Post have new fixed priced satchels for anything up to 5kg. They have done away with the old 500g, 1kg, 3kg, and 5kg satchels. Now they just have different sized bags all up to 5kg. "If it fits, it ships" is the motto. The small satchel is $8.90 and could easily hold 5kg of metal. https://auspost.com.au/shop/product...hel-10-pack-0590825?fm=recommendations:shop:4