There's a company locally doing exactly this and it appears to be either a franchise or a licensee. They've done a lot of special events, school graduations, birthday parties, graduations, etc. Looks like they have an inventory of letters and shapes but no ability to do special shapes or designs. I wasn't able to get close enough to see the thickness of the substrate but I don't think it would have been 3mm Coro. Maybe 6mm. Didn't appear to be 10mm.
Edit: Found the one that is "local" here in Nashville. It's a franchise. It would be interesting to know what the cost of the franchise is and how long the Franchise Agreement lasts.
https://www.cardmyyard.com/