This mobile was easy to make, and I used leftover cardboard from a box, cotton string, white paint and some hardy sticky-tape.
First I traced the outlines of a few different types of birds onto the cardboard. You could draw these yourself or use some templates that are provided online... birds are everywhere!
Then I cut them out, painted them white, drew an eye on each of them, stuck them to the string (see below picture).... and hung the mobile up! As only one side is painted, it is designed to sit flat on a wall.