I believe sections of the Difference and Analytical engines were built. Not the complete project though.<p>I wonder if the designs could have been simplified a great deal if he had known of Turing machines or boolean math. A machine based on Turing&#x27;s original idea, or something like boolfuck, probably wouldn&#x27;t have too many moving parts, though it would be quite slow. I believe Boole even designed a binary calculator that just used marbles and wood seesaws.<p>The greatest expense with the Difference engine was the thousands of tiny mechanical parts required.