Benyamin Ahmed likes whales. He’s also enjoyed coding since he was 5. And those two hobbies have given this 12-year-old a solid base for his financial future.

In July he sold a collection of digital art he coded, called Weird Whales, as non-fungible tokens (NFTs). He’s already made $350,000. And by the end of August, his earnings for those are expected to top $400,000.

Ahmed’s collection sold out in nine hours, earning him a total of 80 Ether tokens, worth about $248,000 at the time. He also collects a 2.5% commission each time those NFTs sell in the secondary market, which have earned him another 30 Ether. At today’s market price, that puts his return at $343,640.

Not bad, considering his startup cost was $300—mostly for gas fees, or the cost of interacting with a blockchain like Ethereum, the public ledger that underpins the cryptocurrency Ether. (It costs money to create, or "mint," NFTs, the act of recording them on a blockchain.) And it’s even more impressive since he doesn’t consider his art skills to be his strong suit.

“I’m not a natural artist, but I watched a few YouTube videos and worked out how to draw whales in pixel form really quickly,” he told The Telegraph.

It’s more than just drawing, though, he said. There's computer science involved in making the graphics unique and in deploying the assets to a blockchain, the public ledgers that underpin cryptocurrencies.

This wasn’t Ahmed’s first foray into the NFT-verse. Earlier this summer he created a collection of 40 avatars called Minecraft Yee Haa. That batch didn’t sell so well or so fast, he said, but it was an invaluable learning experience that contributed to the creation of Weird Whales.

Ahmed is already at work on another NFT project. He has treated himself to a few pieces of digital art with his earnings, he said. What he hasn’t yet done, though, is convert the cryptocurrency he was paid into traditional cash, as he told CNBC. In fact, he doesn’t have a bank account.