I would recommend for all to learn more about this.
Also - search this forum - I think there was good thread about this topic.
Copyright is generally for artwork, music etc... you can't copyright functional object (there are some exceptions for jewelry - but this again goes for decorative aspect of it - not functional)
So you can copyright a photo of the object - but that does not mean object is copyrighted.
So you are stuck with patents... there are "Utility" patents and "design" patents. "Design" patents are protecting just exact likeness of the object. Not general idea.
"Utility" patents are general protection - and it certainly can be denied if examiner (yes, there is real human examiner who will look at it) decides there is patent out there already covering similar thing (say, specific clasp for jewelry)
Currently - you can expect about 1.5 to 2 years of wait to get the patent. (in USA). So doing patent is not for faint of heart.
And it certainly means that - if you don't have money to pursue court action - patent is not big protection in itself - but it will give you crucial advantage in case of lawsuit (but, again... make sure you have $$$ to get to court in the first place.
In short - patents are not very designer friendly at all. It's a system that badly needs fixing.
But if you think you are somehow protected just by saying "copyright" - no you are not, not at all.
For reference, I worked for medical company for eye cornea related device design - patent and attorney costs to get patent were about 75.000 $ and it took 2 years. Of course medical industry is extreme example, they sure have money - but they really do NOTHING before they secure patents, because such protection is very important there.
One thing you need to know about having patent... if, say, big company such as "Kartell" wants to license your 3d printed lamp - you are in MUCH better position to negotiate better licensing deal if you have a patent (or can prove you applied for one - so called "patent pending"). Such big companies will not talk to you without it most of the time... or will ask you to give them full permanent rights instead of license.
So hey.. good luck.