Apartment From Ping-pong Balls, Brooklyn, New York City, United States

The walls in this tiny 90 square feet (8,36 sq. m) apartment in Brooklyn were decorated with 25,000 ping-pong balls. The apartment was built in two months for less than $100 a square foot.
Table tennis
Table tennis, also known as ping-pong, is a sport in which two or four players hit a lightweight, hollow ball back and forth using table tennis rackets. The game takes place on a hard table divided by a net. Except for the initial serve, players must allow a ball played toward them only one bounce on their side of the table and must return it so that it bounces on the opposite side. Points are scored when a player fails to return the ball within the rules. Play is fast and demands quick reactions. A skilled player can impart several varieties of spin to the ball, altering its trajectory and limiting an opponent's options to great advantage.