Wow... I'm glad to see I'm not the only one that hates humans.
anyway.
Hope you catch the crook.
Since I don't trust ANYONE, May I suggest keeping a small cheap digital camera, photograph EVERYTHING you make (even if its garbage) from two sides. That way you have DOCUMENTED that YOU made it and not some other creep.
Try to get a pic with you holding it showing your initials carved in it, then even if they change it you still have proof..
I talked my stepson into pressing the side of his highschool class ring leaving a small impression that only HE knew ment anything but to casual observer just looks like a mark.