Using concepts for practice

Zelfit

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?

Shiniku

Generally, asking for permission is the right move. If they don't respond, I say go ahead and do it anyway, just be sure to credit the concept artist anywhere you post it. There's always a slim chance the artist will find it and ask you to take it down, but I've never heard of that actually happening

Popol

You still sent a PM to the author, which was the polite thing to do.

So just make the character, you're not doing anything wrong as long as you don't make a commercial use of that character. But don't forget to give credit to the concept artist once you put the finished character in your portfolio.

ZacD

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 is a "new work", and studies and practices shouldn't ever be an issue.

HitmonInfinity