Tesla has officially opened its video contest just four days after Tesla CEO Elon Musk replied via Twitter to 10-year-old Michigan girl’s letter erroposing the idea.

The all-electric automaker and sustainable energy company launched “Project Loveday” at midnight Saturday, allowing Tesla fans to submit a 90-second video. The project is named after Bria Loveday, who penned a letter to Musk, suggesting the company launch a homemade commercial contest.

Musk responded on Twitter, praising her idea as “great” and promising to implement it. “We’ll do it!” he wrote.

Thank you for the lovely letter. That sounds like a great idea. We'll do it! https://t.co/ss2WmkOGyk

— Elon Musk (@elonmusk) March 2, 2017

The contest is notable because Tesla doesn’t advertise in the traditional ways other automakers do with TV, radio, and online commercials. The company’s marketing efforts are more nuanced, relying on the fervor of its owners to spread the word as well as social media, including Musk’s own Twitter account, which has 7.57 million followers.

The fine print of Project Loveday lays out the rules and how winners will be picked. The contest officially began at midnight Saturday. Participants can submit their entry until May 8.

Videos can be no longer than 90 seconds and must relate to Tesla, SolarCity, the company’s products, or its mission to “accelerate the world’s transition to sustainable energy,” the company says in its rules. Participants must fill out an entry form and a YouTube link to the video.

All submissions will be judged by Tesla personnel, the company says without specifying who or how many judges there will be.

Ten winners will be selected based on originality, creativity, relevance to Tesla and its mission, and entertainment value, the company says. Those top 10 submissions will be featured and shared on Tesla’s social media channels.

The judges will then winnow the list to the top three scores. Those three winners will receive additional promotion across social media channels.. The highest score will be named “grand prize winner.” This grand prize winner will be invited to and introduced at a future Tesla product launch event. Tesla will pay for reasonable travel expenses and accommodations for two people for two nights to attend this future event, according the official contest rules.

Winners will be announced on or about May 22, 2017, according to Tesla.