On MakerWorld, a user named Subsy has uploaded a 1:1 iPhone Fold replica (via Macworld), which can be 3D printed to give you a rough idea of the size of the upcoming foldable iPhone.
Subsy claims that the model is "based on recently leaked CAD drawings of the iPhone Fold," but there haven't been actual CAD leaks to our knowledge. There were reports of CAD drawings earlier this month, but it turns out those drawings were concept drawings and renders created by MacRumors reader iZac back in May.