LEGO Difference Engine
Babbage never got a chance to build his difference engine. Ironically it is considered one of the most advanced and is arguably the most famous of these old mechanical computers. One was eventually made in 1991 for the Science Museum in London. Don't live in London? Too far to drive? Well, no worries, Andrew Carol has built a working difference engine from LEGO's and with a kind donation of server space from Steve Wozniak, he's posted a very detailed explanation of his project so you can build one too!