The coin was cast - melted gold was poured into a mold - rather than the normal process of mass-creating coins (stamping the design onto a plain metal disc, called striking).
News articles say that this is now the largest gold coin in the world, and is 10 times larger (by weight) than the previous record holders.
The Perth Mint has a Web site at 1tonnegoldcoin.com with a video of how the coin was made (also embedded below) and pictures, but surprisingly little other information about the coin or why it was made. There are many news articles about the coin, such as:
Don't think about trying to get this coin for your collection. I don't think Australia's going to want to let this coin out of its sight. And I can guarantee that there isn't a coin flip big enough to properly store this giant.