I was searching for some interesting character concepts for practice to make it in 3D. I found one that I like on Deviantart. I sent the author PM, but he didn't answer. Do I need any permission if I'm making the character for my own practice and not going to use anywhere, except my portfolio?
If you are not making a profit and you credit it original artist, it should be fine to use any concept. I think falls under http://en.wikipedia.org/wiki/Derivative_work I'd still always suggest trying to contact the original artist just to avoid any legal drama, even though I think using a concept for a 3d project clearly…