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I don't see anything wrong with the site. You have good titles and meta descriptions as far as i can see. You have the Open Graph meta tags and i don't see any problems. You said your impressions are going down. Maybe you should broaden your audience? Google+ Communities is a good place if you're not active in one or several communities. I'm pretty sure there are some good communities on 3D subjects. I didn't find a link to your Pinterest account on the site. Pinterest might seed your needs because i see a lot of cool images and videos in your articles. You might find a better audience there. Hope i gave some valuable advise which you can work with.