These are all the materials you will need. Ask for 'architect prints' at an office store.
We found the foam board at Home Depot. It is foam insulation. We had them cut it into pieces so it would fit in our car.
Crayons work better than colored pencils for coloring over black and white.
It was a really easy and fun way to get something more California feeling up on our walls. Along with the fact that it was super cheap. The foam board was only $2! We even had extra foam board, so we taped the edges and now use it as a bulletin board for ideas.
We wrapped the picture around the foam board (like a present) and taped the back with duck tape so the edges would look nicer. To hang the pictures we put tiny nails into the wall and stuck the foam pictures right into the nails. This method of hanging worked better than any other method.