The Mooncaster is a Fender Starcaster clone, so you'd think there'd be cases specifically for them, but no. At least, not new ones. If you search around the interwebs, you'lI see more than one recommendation for a
Silver Creek Vintage Archtop Hollowbody Guitar Case. As it happens, I have one here for a Mooncaster I'm putting together, and while it's a nice enough case, the guitar basically swims in it. Plus, it doesn't lay flat because the neck support closer to the heel is way too tall. So, we're gonna have to make some changes of some sort as this lovely is going to have to travel just about as far from here is it could go without leaving the planet.
If you look at the second from the last post in
this thread, there are a couple pictures of a Starcaster in two different cases (one for a Gibson Lucille, and another for a Yamaha SA-1000) that look to be much more suitable. Good luck finding the Yamaha case, and I suspect he's wrong about the Gibson case being for a "Lucille" (ES 355). Those are roughly the same size as 335s, which are bigger guitars.
Sorry I couldn't be more help, but at least we're narrowing things down. Eventually, somebody's gonna find just the right thing, as I don't think Warmoth is going to give up on Mooncasters any time soon.