Elon Musk -- co-founder of PayPal, creator and CEO of SolarCity (NASDAQ:SCTY.DL), Tesla Motors, and SpaceX -- rocked the world once again this week, when he announced a plan to build a "Hyperloop" mass transit system in California.

According to Musk, the Hyperloop would be a pair of elevated, fully enclosed transport tubes, powered by sunlight and stretching hundreds of miles in length. Initially, it would connect the major California major cites of Los Angeles and San Francisco, shooting electromagnetically accelerated "pods" full of passengers between the cities at speeds of up to 800 miles per hour -- and at a total cost of only $6 billion to build. Over time, other Hyperloops could be built among other cities -- so long as any two locations are within about 1,000 miles of each other.

California legislators immediately rejected Musk's idea, saying they'd rather spend tens of billions of taxpayer dollars on a high-speed rail system already in the works. But legislators such as State Senate Transportation Committee Vice Chairman Ted Gaines suggested Musk would be more than welcome to try to build a Hyperloop ... so long as Musk is the one paying for it.

And that gets a lot of investors to thinking: Well? Why not? Thanks to the astounding success of the stocks in companies Musk has founded already -- Tesla and SolarCity -- Elon Musk is now one of the richest men on the planet, boasting a net worth that some have estimated at $7 billion. With that kind of money, he could quite literally build a Hyperloop on his own dime, and still have $1 billion left over.

Of course, as CEO of not one, not two, but three separate companies, Musk doesn't have a whole lot of free time available these days. Here, then, are a few ideas for companies that might have the time, and the ability, to help Musk turn his Hyperloop dreams from hype into reality:

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