TT23,
In theory you don't "build" a wormhole. If you have a spinning (and preferably charged and spinning...Kerr-Newman) black hole it should have a wormhole associated with it.
If you want to be able to traverse the wormhole the theories say you have a problem. Any mass-energy that falls into the worm hole causes it to collapse.
When Carl Sagan was writing "Contact" he contacted Kip Thorne and asked him how to build a proper time machine using a worm hole. Thorne took the question seriously and, together with his grad students, they pondered the question. From that they developed a theory of "exotic matter."
This specific "exotic matter" has the property of anti-gravity. If you line the throat of the wormhole with exotic matter it "pushes" against the collapse and keeps the hole open.
Problem 1: So far there is no evidence that exotic matter exists or can be artificially made.
Problem 2: If you had exotic matter how do you line the interior of the hole with the stuff? (Another problem for Rainman's engineers.
)
BTW: Trust me, the above explanations of "exotic matter" are crude and simplistic...at best. I don't believe that Thorne or Visser would say that exoric matter really is exibiting anti-gravity. They would classify it as having a negative energy density. Even the use of "a theory" of exotic matter is very imprecise. It's not a theory in the sense of General Relativity. It is missing a "few" pieces. /ttiforum/images/graemlins/smile.gif
PS: Well, this should teach me (again) to read the entire thread first. Iq already covered this subject.