Autodesk's Idea to Knit the Hyperloop Out of Carbon Fiber  

BusinessWeek has an article on a proposal to make Elon Musk's hyperloop idea even cheaper - Autodesk's Idea to Knit the Hyperloop Out of Carbon Fiber.

The tube in Musk’s plan is made out of prefabricated steel sections that must be welded together. Critics have pointed out that could leave the Hyperloop prone to air leaks, which would undermine the internal low-pressure system it needs to run. Brandt, who studied building technology at Harvard University and holds the title of technology futurist at Autodesk, proposes making the tube out of one very long stretch of braided carbon fiber infused with an epoxy resin. The strong, lightweight material is used to make everything from jumbo jets to race cars.

There are machines that can churn out limited qualities of the braided carbon fiber. Brandt envisions building a supersize version and mounting it onto a rig loaded with reels of carbon fiber so it could roll along the Hyperloop’s route. Working at a rate of 1 meter per minute, this factory on wheels could weave a Hyperloop tube from Los Angeles to San Francisco in less than two years, and, says Brandt, require fewer support pylons. “Elon’s estimate calls for about $2.6 billion for concrete, but we’d get that down to more like $1.5 billion,” he says.