Use old maps with special significance.
Cut the map to the shape of your coaster using a craft knife then paint the coaster thickly with water-based glue.
Paste on the map and smooth out bubbles and flatten under a pile of books until the glue is dry.
Trim the edges neatly.
Spray with clear varnish to seal (in a well-ventilated place!)
Tie them into a stack ready to gift.