In 1770, Buell moved to New Haven, Connecticut and went to work for cartographer Bernard Romans. After the American Revolutionary War ended, Buell used the minting machine he had invented to mint the State of Connecticut's first official copper coins. Connecticut coppers were struck from 1785 to 1788 by Buell. Buell engraved the dies for the Connecticut copper coinage as well as the dies for the Fugio cents - America's first coinage. By 1784, Buell cast his own typeset and published the first American-made map of the United States. The wall map measured 43 × 48 inches, was printed in four sections, and hand-applied watercolor gave the map its color. In 1789, Buell went to England on behalf of a group of investors to steal the secrets of cotton manufacturing from the British and bring that knowledge back to America. While there, he gained both practical knowledge and a sum of money that allowed him, upon his return, to establish one of Connecticut's first cotton mills.