Submit a Design Patent through the US Patent and Trademark Office. But the argument is that it may not be worth it.
It's not that the patent wont protect you, it's that most people won't have the money to process a patent infringement case.. i've read it could take about 250k to process till the end... if you actually have a patent and can find the right lawyer to fight for you, if the company that is using it has deep pockets, then at least the patent may cause a shortened negotiation period unless they just don't care about how much they are paying their lawyer.
Rule of thumb, if you want a patent, get a patent... If you expect that it will totally protect you, don't expect that.