The man best known for revolutionizing space travel and making the electric car the epitome of cool, is now planning to release his design for a tube transport system capable of speeds up to 1,200 km/h.

Elon Musk, CEO of SpaceX and chairman of Tesla Motors, announced recently on Twitter he will reveal plans for his Hyperloop transportation technology next month.

"Will publish Hyperloop alpha design by Aug 12. Critical feedback for improvements would be much appreciated," he tweeted.

Musk has been secretive about his plans until now, which is why the Aug. 12 date is such a big deal. He once described the concept as a "cross between a Concorde and a railgun and an air hockey table," that could get people from Los Angeles to San Francisco in less than 30 minutes and would cost one-tenth the amount a high speed rail line would take to build.

But so far no one has seen so much as a rough sketch of how the concept would work.

However, engineer John Gardi recently came up with a design of what it might look like. He tweeted it to Musk, asking for some "basic clues" to help him get on the right track: "What diameter of tube so I can start designing stations and throughways?" Gardi asked.

Musk replied that "your guess is the closest I've seen anyone guess so far. Pod diameter probably about 2m."

The 42-year-old South African entrepreneur -- Musk's mother is Canadian and he studied at Queen's University for two years -- reportedly first became interested in alternative speedy travel options after looking at California's high-speed rail plans. The project there is expected to cost $70 billion, but would still be one of the slowest "high-speed" trains in the world.

The Hyperloop would cost far less, would be safer, and could theoretically run on solar power, Musk has said.

Most experts believe Hyperloop would function similarly to the vacuum tubes used to send messages through large offices before the days of email. And it would use magnets to suspend the pods inside the tube, meaning no friction and no wind resistance.

But, until Musk’s big reveal on Aug. 12, it's mostly speculation.

He said recently that he doesn't believe in patents "unless critical to company survival," and said he will publish the Hyperloop design as open source, meaning anyone can access the plans and tweak them to their own liking.

"Happy to work with the right partners," Musk added on Twitter. "Must truly share philosophical goal of breakthrough tech done fast & w/o wasting money on BS."