There are many things you can do for extra time:
The best method for extra source of income is to coin your potential in to art.
By knowing your talent not only you will have extra income but it may leads to long life happiness.
Let me put few profession for part time-
Consultancy- related to your knowledge.
Teaching: Occasionally (online or offline)
Share market or stock investments
Sell online products
Social media promotion
Use cashback or rewards
You will just need to have time for yourself to understand what can you do in what you have.
You can create better things around you, which will get you profit.
Source: Ankit Kumar (Q)