I've looked over and over and can't find it. Did it ever exist on the app store or did it just get taken down?

Drew said he found it, but I can't see it anywhere. I'm in the UK, though.

Hm, this is the only reference to an iOS version that I've been able to find.

Yes, as recently as September 13th, but it was removed from the US itunes store shortly after then.

http://appshopper.com/games/boxmaker

https://itunes.apple.com/us/app/apple-store/id1058520196

If you change your itunes region to China you can follow this link for a working version. https://itunes.apple.com/cn/app/boxmaker/id1058520196 You'll need a Chinese itunes account to download it, though that's easy to get.