1. Sell matter and other resources in the Trade Portal (profit 200c per day). Resource piping is easy to customize. Due to the portal limitation, it is necessary to create an additional source of income or use larger land plots to create additional portals.
2. Offices earn 120-240c per day. This requires 45-90 workers (and their maintenance) and 18-36 power. There are other money buildings like banks, town squares, entertainment centers, but they earn less than offices.
3. The most profitable is the sale of resources to neighboring cities. But you have to make sure that your neighbors can afford to pay for this resource. They need their own source of income.
4. There are also social gatherings in the game. They require a large population and high prestige. At first, the income will be small, but when the population is 200 or more, the profit will increase.
5. Earn tourism income with airport and zeppelins.
6. The most effective method is borrowing money, earning interest by waiting.
