Where can you sell print-on-demand physical products like t-shirts and sweatshirts?

Merch by Amazon is the correct platform for selling print-on-demand physical products like t-shirts and sweatshirts. It allows creators to upload designs, and Amazon handles the printing, shipping, and customer service. Kindle Direct Publishing (KDP) is for publishing ebooks and paperbacks, not physical merchandise. Amazon Vendor Central is for manufacturers and distributors to sell directly to Amazon retail, not for individual print-on-demand. Amazon Seller Central is for third-party sellers to list and sell their own inventory, which could include print-on-demand items if you manage production and fulfillment yourself, but Merch by Amazon specifically streamlines the print-on-demand process. Amazon Brand Registry helps brand owners protect their intellectual property and control product listings, but it's not a selling platform itself.