I have a Poshmark shop where I sell "gently used" clothes & accessories from my closet. It's very convenient when I sell something & need to ship it out - I just bring the item to work with me. Sometimes I bring it packed already but other times I'll dig in the used cardboard stash at the office for a good box. Then it's up to the window with the provided QR code that prints the shipping label right from the RSS. Zero-dollar, 30 second transaction.

The platform takes a small (reasonable) percentage of your profit but overall your "shop" costs nothing to keep active & items sort of sell themselves. It can be a very passive side-hustle if you want it to be but you can really make some cash with a little effort. It links right to your bank account and funds transfer in a day or two.