I happened to read some articles on "habitable zones" (for the idea of location
of beginning of intelligent life in the universe) and also available energy
sources in the universe, along with re-reading some articles from "The Science
in Science-Fiction" and USBornes Book of the Future".

It is possible that even if the material technology were capable of it, there
would not be that much interest in building such things as Dyson Spheres or
Rings beyond as god-like art works. If a society has sufficient matter-energy
manipulation ability (whether or not they have faster-than-light travel
ability), perhaps the place to get the energy and matter would be to head
straight (more or less) toward the center of the galaxies where the creation and
destruction of stars (and the associated high atomic number matter) may be
taking place at a rapid rate. There is also the possibility of collecting the
energy from the "active galactic nucleus" by way of its relativistic jets and
accretion disk.

Perhaps a "search for intelligent life" might get better results by looking
toward the center of galaxies for signs of relatively large scale "mining
activity".

Those with the ability to do faster-than-light travel and sufficiently external
manipulation of space-time might even "scoop up" some of the nucleus resulting
in tiny black holes that can be used as fast decaying micro-black holes (subject
to the limits of the technology hold, manipulate, and "feed" it). Some might
consider how the "anti-grav" device in VDS supplement might be altered to help
achieve this, possibly by holding a planet-equivalent mass black hole and using
very tiny "scoops" to flash out matter-energy as needed, making it far better
though correspondingly more dangerous than the "anti-matter" fuel type.

An idea for logistics economy for those with faster-than-light transportation
(and a sufficiently cost-effectiveness) could include getting matter-energy from
galactic cores as mentioned above. Outer parts of solar systems and more
distant areas could be useful for various large-scale cryogenic manufacturing
and processing. Maybe certain quantum-mechanical processes are best done where
it is near absolute zero on a large scale.