The desk in front of the Slime Tower in the center of the Casino will let you trade your G for Tokens. There is a Bunny Girl who will explain how the Jackpot works by the large Slime Tower in the center of the Casino. When you enter, there is a Bank on the upper-right balcony, and the Exchange Counter on the upper-left.
I gain about 20k coins every 10 or so minutes, especially when getting to metal mode. Continue reading A Comprehensive Guide to Easily Farm Gold in Dragon Quest 11: The Best Methods Revealed