Unfortunately as soon as you put your designs out there, they're up
Domestically you can do something, but internationally you'll come
across difficulty. Troll vs. Pandora for example (sorry if this is a
sore point for anyone, but it's a very good example).
You can pay money (a substantial sum of money) to protect your
designs, but unfortunately there are some countries that don't give a
tinkers cuss and will take your design regardless of whether the
design is protected or not.
What you can do is make sure you're first. Make your product as
visible as possible, stating that you created these designs, and be
know as first creating them.
Unfortunately if someone wants to copy what you do, internationally
you can't do much to protect it.
Sorry for the bummer
The upside is that you "could" feel flattered that someone thought
your designs exceptional enough to steal :-\
Regards Charles A.