It seems few people are busier than Elon Musk. The 45-year-old billionaire, who made his fortune through the sale of PayPal to eBay in 2002, is as much an entrepreneur as he is an industrialist, a futurist and a talented engineer.

He wants to take electric cars mainstream, reinvent solar panels, help develop a 700mph levitating train, and take humans to Mars. He also, as his current to-do list shows, has a love of tinkering in the shed on everything from Tony Stark's computer to James Bond's Lotus submarine.

Here is everything we know Elon Musk is working on right now, or has been working on in recent years. Prepare to feel rather unproductive...

1. Tesla

Musk's electric car company is what he is best-known for. Founded in 2003, Tesla has produced three cars (the Roadster, Model S and Model X), and will begin selling its fourth car, the Model 3, later this year. It will then launch the Model Y and is already working on Tesla-branded trucks and small mass-transit vehicles similar to buses.

Tesla, which delivered around 76,000 cars in 2016, has already received over 400,000 pre-orders for the Model 3, which will be its cheapest car yet at around £35,000. As well as producing electric cars, Tesla is leading the way (publically, at least) with its self-driving system, called Autopilot.

Elon Musk
Tesla boss Elon Musk could be the most forward-thinking engineer for a generation Reuters

2. Solar panels

Tesla already has its own charging network, but this isn't the long-term goal for Musk. After merging Tesla with SolarCity, a solar panel producer of which he was chairman, Musk revealed a range of roof tiles which collect energy from the sun, but look like normal roofs. Once on sale, they will charge up a customer's Tesla Powerwall, which then provides power to the house, or recharges the car each night, taking the owner partially 'off-grid'.

Tesla solar roof
Tesla's solar roofs look like normal tiles, but can be used to power a home and charge a car Tesla

3. Project Goldfinger

We really don't know much about this one, but it sounds like the kind of thing James Bond-fan Musk would work on in his spare time. A recent tour of Tesla's California factory unearthed a sign reading: "Top Secret: Project Goldfinger", attached to a sealed off area where photographs are forbidden. Musk said later the sign was "probably a joke", but at this stage we can't put much past him anymore.

4. SpaceX

A private space transportation company, SpaceX is busy creating reusable rockets which can return to base and land themselves, dramatically reducing the cost of firing cargo into orbit and to the International Space Station. In 2016 Musk outlined his plans for colonising Mars.

Musk wants to reduce the cost of human spaceflight by a factor of 10 and land humans on the surface of Mars within the next two decades; he believes he and SpaceX can establish a Mars colony of up to 80,000 people by 2040. Watch any presentation by Musk on space travel and it's clear how he genuinely believes humanity faces an existential threat if it doesn't begin to populate The Red Planet. Musk once said he wants to die on Mars, just not on impact.

5. The Boring Company

Stuck in traffic, Musk wondered if he should start digging huge underground tunnels for roads and train lines. This being Musk, an enormous hole had been dug outside his office just a few weeks later, and he claims he can speed up current tunnel boring techniques by between 500 and 1,000%.

Musk suggested he might set up The Boring Company, and how the tunnels could be used for roads to ease traffic congestion, or for high-speed railways, which brings us to his next side project:

6. Hyperloop

HTT Hyperloop
The Hyperloop designed by HTT uses a magnetic levitation system to reach speeds of over 700mph HTT

Outlined in a white paper in 2013, Hyperloop is a train designed by Musk which levitates on magnets and is propelled through a tunnel with most of its air removed, at over 700mph. The idea was presented by Musk as an alternative to a "high speed" train line planned to connect Los Angeles and San Francisco. This $60bn (£48bn) project commissioned by the US government would travel at 130mph, while Musk claimed a Hyperloop would cost a tenth of the price, yet travel almost six times faster.

Musk isn't being too active with Hyperloop, but through SpaceX recently organised a competition for companies and universities to show off their own ideas of the futuristic train. Meanwhile, two companies (Hyperloop One and Hyperloop Transport Technologies) are both working on making it a reality.

7. Advisor to President Trump

Musk is a member of President Trump's advisory team. Despite criticism from some corners over his staying in the role after Uber boss Travis Kalanick quit in the wake of Trump's immigration ban, Musk claims his relationship with the White House is a good thing, and that his position there is already making a difference.

"Advisory councils simply provide advice and attending does not mean that I agree with actions by the Administration." Musk said in defense of his role, adding that he will remain for "the greater good".

8. A human brain/computer interface

Now we take a trip to the far side of Elon Musk's to-do list. A place where someone who thinks colonising Mars is completely normal gets to let their imagination run wild.

The first of these has been dubbed a "neural lace brain hack", whereby human brains and computer systems can be somehow linked together, achieving a "symbiosis with machines". Musk is worried that, as artificial intelligence (AI) evolves and becomes capable of taking human jobs, we could become little more than "house cats". To prevent this, he wants to add a form of digital, computerised intelligence to our brains, helping us communicate with AI.

Musk tweeted in late January 2017 to say he might have something to announce on the neural lace "maybe" in February.

Tesla Motors CEO Elon Musk
Tesla boss Elon Musk took to sleeping in the factory while fixing faults with the new Model X car Beck Diefenbach/Reuters

9. OpenAI

Created by Musk in late 2015, OpenAI is a not-for-profit artificial intelligence company which aims to develop AI in a way which is both safe and beneficial to humans. Musk, along with Stephen Hawking, has previously revealed his concerns that one day AI could evolve to such an extent that it poses a threat to humanity – and not just taking our jobs.

He went so far as to describe developing advanced AI as "summoning the devil" if precautions weren't taken. Ironic, perhaps, for a man who owns a car company which prides itself on its advanced artificial intelligence.

OpenAI wants to "counteract large corporations who may gain too much power by owning super-intelligence systems devoted to profits, as well as governments which may use AI to gain power and even oppress their citizenry."

10. Tony Stark's computer

Musk is often compared to Tony Stark, also known as Iron Man, thanks to his billion-dollar bank balance and engineering expertise; Musk also made a brief cameo in the film Iron Man 2.

In August 2013 Musk tweeted to say he and his SpaceX team had come up with a way to design rocket parts with hand gestures, then 3D print them in titanium. When asked "like in Iron Man?", Musk replied in his usual matter-of-fact way: "Yup. We saw it in the movie and made it real. Good idea!"

11. James Bond's amphibious Lotus Esprit

And October 2013 (and presumably because coming up with the Hyperloop and building Iron Man's computer wasn't enough for one year) Musk bought a car used by James Bond.

Musk paid £616,000 at auction for the Lotus Esprit submarine used by Bond (Roger Moore) in 1977's The Spy Who Loved Me. The film included a Lotus which, at the push of a button, switched from car to submarine, and back again. Although this was never a reality, Musk believes he can make it transform from car to submersible – and be powered by a Tesla motor, naturally.

James Bond Lotus Esprit Elon Musk
Musk paid over £600,000 for the movie prop, which he wants to turn into a real amphibious car RM Auctions

"It was amazing as a little kid in South Africa to watch James Bond drive his Lotus Esprit off a pier, press a button and have it transform into a submarine underwater," Musk said in a statement after he bought the car. "I was disappointed to learn that it can't actually transform. What I'm going to do is upgrade it with a Tesla electric powertrain and try to make it transform for real."

Nothing more was said until June 2016, when Musk tweeted: "If curious about The Spy Who Loved Me car, am still planning to do a sports sub car that can drive on roads. Just a side project. Limited market potential."

If he can get the car to work, Musk said: "I'm treating myself to a volcano lair. It's time."

At this point, who are we to doubt him?