The Cybertrucks that never came to be: This newly shared photo of Elon Musk shows early, more curvy designs for Tesla's truck in the background

• Walter Isaacson shared a photo that provides a rare peek at Tesla's early Cybertruck designs.
• The biographer's picture shows that some ideas for the truck were curvier and more conventional.
• The picture also highlights some of the films and video games that inspired the Cybertruck's design.

Ever wondered how Tesla came up with the design for its futuristic Cybertruck? Elon Musk's biographer shared a photo that appears to include a rare peek at early design ideas for Tesla's Cybertruck — and it wasn't always so angular or unconventional.

Walter Isaacson, who has been trailing the Tesla CEO for about three years, shared a photo of Musk and Tesla design chief Franz von Holzhausen on Twitter Tuesday. In the background of the photo, there are several pictures of what appear to be early design ideas for the Cybertruck, as well as photos of popular films and video games that inspired the vehicle.

In his Twitter post, the biographer shared some quotes from his book, "Elon Musk," which is set to be released in September.

"The Chevy Silverado was still on the showroom floor for reference," Isaacson wrote on Twitter regarding the photo. "In front of it were three large display boards with pictures of a wide variety of vehicles, including ones from video games and sci- fi movies. They ranged from retro to futuristic, sleek to jagged, curvaceous to jarring."

Some of the early sketches for the Cybertruck appear much more curvy and traditional than the sleek, angular design of current Cybertruck prototypes that have been seen in action. Though, all of the images appear to have a futuristic slant to them.

Even a scaled back early design of the Cybertruck looks out of place next to a Ford pickup truck. Isaacson told CNBC's Squawk Box on Monday that Musk was inspired to create the Cybertruck in the first place about six years ago because he thought Ford's trucks were "boring."

Other pictures on the board appear to be more reminiscent of Tesla's current design for the electric pickup truck.

Isaacson said on Twitter that Musk gravitated to the designs that had a "futuristic, cyber look" and was determined to not play it safe. The biographer said Musk had been "talked out of some of his more radical and unconventional suggestions" for Tesla's Model Y SUV.

"'Let's be bold,' he said. 'Let's surprise people,'" Isaacson wrote of Musk's comments on the Cybertruck design. 

The board in the picture includes pictures from numerous movies and video games, including "Back to the Future's" DeLorean, James Bond's Lotus Esprit 1 Series submarine car from the 1977 film "The Spy Who Loved Me," images from "RoboCop" and "Tron," as well as stills from "Cyberpunk 2077." Isaacson said on Twitter that Musk was most intrigued by the futuristic ideas and pointed to stills from Ridley Scott's "Blade Runner" or the video game "Halo."

"His son Saxon, who is autistic, had recently asked an offbeat question that resonated: 'Why doesn't the future look like the future?'" Isaacson wrote. "Musk would quote Saxon's question repeatedly. As he said to the design team that Friday, 'I want the future to look like the future.'"

Despite some pushback from others at Tesla, Musk said he wanted to build the truck how he envisioned it and didn't care if "no one buys it," Isaacson wrote on Twitter. The biographer said Musk issued an edict in 2017 that the pickup truck would be entirely stainless steel — making it edgier and futuristic.

Last week, Tesla shared that the company had made its first production Cybertruck at its Texas Gigafactory. Musk first unveiled the concept for the electric pickup truck about four years ago and the project has faced a series of delays over the past two years — which some have attributed to the vehicle's unusual design. Most recently, the CEO has said the company plans to start delivering the Cybertruck within the year.