- BookBlock - custom-cover hardcover notebooks
- Dynomighty – print your own, custom-pattern Mighty Wallet
- The Studio – batch order/make caps, socks, patches, bags, aprons, pins...
- JiMi Agency - batch order/make charms, stickers, cards, washi tape...
- Printful – prints shirts/posters/leggings/totes... connects to Gumroad, Big Cartel, etc.
- Society6 - prints shirts/posters/totes/pillowcases...
- Teepublic - T-shirt printers, recommended by paperbeatsscissors
- TopatoCo - makes shirts, books, plushies... but only accepts already-established creators
- Soft Stuff Creations have been recommended by folks in the comicscommunity for plushies
- Squishable for plushies
- Happy Worker for plushies
And last but not least, check out this great Twitter thread about sticker printers.