If you file a tax return for any reason you must report all your income, no matter how small an individual item might be. This includes hobbies.
The IRS test for hobby or business is here. There's no set dollar amount, it depends on intent and actions.
https://www.irs.gov/newsroom/heres-how-to-tell-the-difference-between-a-hobby-and-a-business-for-tax...
If this is a hobby, you report the gross sales proceeds as taxable hobby income, which is reported as "other income" on the tax form. You can't deduct any expenses.
If this is a business, you report the gross sales on schedule C, deduct ordinary and necessary expenses, and pay income plus self-employment tax on the net profit.
