Worrying about protecting your designs is mostly a waste of time. Creating art is like sports. What you did before isn't nearly as important as what you can do next. It's hard to live off your past performances.
For any artist that is trying to get their work into a quality gallery or to be handled by a good professional sales agent, the MOST important consideration in getting accepted is expected future productivity.
The important consideration is whether the artist is driven to constantly innovate or is the artist more likely to want to live on the residuals of a small few designs?
A good artist can create a few original ideas.
A great artist spews them out like water from a running faucet.
Some complain constantly about how hard it is to come up with new ideas and spend most of their time examining the work of others to find ideas to "borrow". Others complain about how impossible it is to find time to implement other then a miniscule fraction of the ideas pouring from their ever creative minds.
The ones that can only originate a limited few designs are ever protective of their small collection.
The ones that innovate constantly couldn't care less who copies them.
The people that buy the work will respect the artists that want to protect their work - but they'll buy the work of the artists that are more concerned about creating the future then protecting the past.