Broadly speaking, if you are engaged in a side hustle with a profit motive, and you engage in the activity regularly, it would be considered a self-employment business. If it is occasional, not for profit, not regular, then it is probably a hobby.
If it is a business, you must file a self-employment return if your net profit is $400 or more, even if you have no other income. You would pay self-employment tax, but you don't pay income tax unless your total taxable income is more than $15,000.
If it is a hobby, your profit is still taxable. You can't deduct expenses (like shipping, if you were doing this online) but you can subtract the cost of materials. If your materials are $50 and your proceeds are $210, you have $160 of taxable income. If this is your only income, you don't need to file a return. But if you file a tax return for any reason, you must include all your income even if some items are small. You would report this as miscellaneous other income.
See this,
https://www.irs.gov/newsroom/hobby-or-business-heres-what-to-know-about-that-side-hustle
This answer has been verified for accuracy by an Intuit expert employee
