What kind of printer do i need to do direct imaging on a postcard? -

If by direct imaging you mean printing directly from a digital camera, then you should get one of the many small portable printers which allow attachment of a camera using PictBridge or have slots to accept memory cards. Google for Photo Printers. They are often sold with cameras by, for example, HP, Kodak and Canon. These printers are often portable and some can run on batteries. They generally print to a maximum size of 6quot; x 4quot; or 7quot; x 5quot;, an ideal size for a postcard. It may be possible, too, to get pre-printed postcard stock (with a space for stamp, address and message printed on the back).