Keep in mind that 3 years really means 30 game turns. And, you are only getting it that fast by using emergency build at 11 spaceyard ships. The resources required to build a single ring world are pretty hefty. In other topics, some people have offered up the idea that if you have enough resources to build a ringworld, then you probably have enough resources to conquer the galaxy.
[This message has been edited by raynor (edited 20 February 2001).]