[Q]

At the moment I see no possibility to make the AI build ring- or sphereworlds.
One small tip: use only one space yard ship to build a space yard base on a space station in the sector with the star. If that's done use them to build more space yard bases until you have 11 ( for ringworld) or 21 (for sphereworlds). Then start constructing the components.
Bases cost less maintenance than ship.
Because the ring- and sphereworld placement component takes longer to construct than the rest of the components I use one the first available base space yard to start this construction earlier than the rest. If some components would be completed before all other components are ready put their space yard on hold until the rest of the constructions catch up.