Do the borders actually help the appearance of the postcard? Me I'd make em borderless as most postcards I've seen bleed off the edges. I made an adhesive borderless easel once using a thick sheet of plastic and glued down some edges to line up the paper to and put several strips of Post-it tape down on it to keep the corners of the paper down. I think the stuff is available at office supply stores, I got mine from work. I laid a sheet of paper the size I was using down, set it against the corners and outlined the sheet with a pen, then I had something to aim the enlager at.