Here's a few of the ideas from Mr. Jacque Fresco,
co-founder of Revell Plastics, aircraft & space-station engineer, Futurist & Socio-cyber-engineer -- founder of "The Venus Project".
All these are buildable with 1970s technology.
Nuclear-powered Robotic Laser canal-digger

Constructors for high-rise "pod-housing" & a mini nuclear-reactor
