Obtain the indicated amount of medals in Infinity mode to unlock the corresponding ship design.

Ship design #2: Obtain two Bronze medals.
Ship design #3: Obtain four Bronze medals and two Silver medals.
Ship design #4: Obtain five Bronze medals, four Silver medals, and two Gold medals.
Ship design #5: Obtain six Bronze medals, five Silver medals, and four Gold medals.
Ship design #6: Obtain six Bronze, Silver, and Gold medals.