- Using 4 huge concrete or metal 'elbows', bolt together a torus. Water seal the whole thing somehow. Probably very expensive, and heavy.
- Loop together 8 steel pipes with heavy rope or cable into a circle. Make 16 total. This forms the longitude. For the latitude, make 8 more circles in the correct sizes needed. The following picture shows the longitude in blue, and the latitude in red
It would be best to figure out all the exact lengths of pipe needed beforehand. I'll come up with some measurements soon. Now you have 24 circles total. All you have to do now is tie them all together tightly, probably with big wraps of binding wire at each vertex.
Offered by Joe.
PS: I tried to be clear in the descriptions, if not don't hesitate to ask. I'll be working on models, so please offer suggestions, even if they sound stupid. Stupid ideas are usually the best ones. And no, spraying styrofoam or InstaPak on the outside isn't a stupid idea. Neither is the pink-panther insulation stuff, you can sandwich that between 2 layers of heavy cellophane before concreting. Anything goes.