What the sibling said. You also have to be sufficiently business-like in your projects, according to legal advice I got. If you slap an LLC on your obviously hobby project, they might be able to make the case that it wasn’t a legitimate business operation. That is fraud isn’t the only way to pierce the veil, I was told.
It's not technically fraudulent to use your personal bank account, per se. You need to keep great records though. But from what I understand that could be enough to consider the veil pierced. Also need to make sure you don't personally ensure any debts.