Brittany, as a painter I'm actually on the opposite side of that. Now, I watermark all my images in my Etsy shop and my online website, so that helps. When someone pins one of my paintings, the painting goes out and so does my name and business whether it's pinned from here or elsewhere. It's almost like a virtual business card.
The thing about art is that you're not just selling your painting, you're selling you. You are the brand. So, even if someone does copy it - it's still not done by you, which is how you have to approach selling art. I did just switch to my artworks coming with a certificate of authenticity, because there has been some confusion as my business has grown. But in general, Pinterest only helps get my name out there.
I would think the same could be done with any product here on Etsy, make sure to mark your images with your logo, and then consider it free advertising? Because really, if the person is going to create a copy for themselves they never were going to buy it anyway.
