I professionally manufacture and sell these under the name 'Noteboards', but you can make your own too!
A roll of packing or shipping tape
Some index cards
A flat surface
1. Take a bunch of index cards and lay them out neatly in rows on some kind of impermeable, solid surface -- a table or plastic cutting board, for example. Leave about 1/8" in between each index card.
2. Cover the index cards in a single layer of overlapping strips of packing tape, leaving no gaps in the tape.
3. Peel up all the tape, pulling from the corner of the first strip you put down, so the tape and cards and all come off your working surface as one big sheet.
4. Flip the whole sheet over so the tape's sticky side and the un-laminated sides of the index cards are now up. Then repeat the previous step, so that the index cards are laminated on both sides with sheets of overlapping strips of packing tape.
5. Trim the edges with scissors or a box-cutter. Fold up your Noteboard map-style and secure it with a rubber band. Away you go!
Note: It's really easy to get air bubbles, hair, and dirt trapped under the adhesives. Be sure to test out different dry erase markers on the tape you'll be using before you actually make your Noteboard! Some colors and brands come off much cleaner than others.