A pipelauncher would be something which could lead to space elevators.
I believe that probably the best location for a space elevator is in the ocean and the best "foundation" would be a floating structure.
A pipelauncher would be built to assist the launch of a rocket. The first pipelauncher might add somewhere around 20% to payload mass of a rocket and could be developed so that rocket payloads are evenually doubled- this could be done mainly by increasing the size of a pipelauncher.
I know of no technical reason why a pipelauncher couldn't be 2 km long/tall. If you had 2 km tall pipelaunchers then taking the next step of a space elevator would be such a farfetched idea.
By using the ocean, it allows a techical advantage in construction- you can build HUGE pieces and float them into position in order to join them together. A pipelaucher is essentially a pipe with one end capped- it's only limit as far as depth is the gas used- oxygen would liquify at some point so if you used helium any ocean depth it wouldn't have this problem. {btw, Space elevators would also probably use helium merely to reduce weight of entire structure).
Buckminister Fuller saw floating cities in the sky- I think there will be floating cylinders instead of domes, and they will break the sky.