The short answer is: it's complicated. We print with a Digital Dry Toner, which is a sustainable and eco-friendly option for small runs of personalised cards. Toner printing uses resin, but has a high-efficiency transfer rate without releasing any nasty toxins. It barely creates any waste, and we don't have to chuck any ink at the end of the custom card printing process.
To be perfectly honest, there isn't a completely sustainable ink on the market in Australia. We're always doing our research to provide the best option we can. We've found that Algae Ink is the only option that is truly free of non-renewable resources or chemicals, and we're having chats about how to start printing with it in Oz.