This list of tools is not comprehensive, by any means. But it's a good starting point that will get you making cards with a lot of things you probably already have around the house, or can pick up pretty inexpensively. It will get you a solid start with the least amount of investment. And I'll often tell you when something is a nice-to-have rather than a must, and what alternatives you can find.

Basic Supplies
Other fun items
Your signature, or a special stamped image on the back of the card.
Your working surface
Work Surface with lots of light and a tablecloth or scratch paper to work on