Is is copyright infringement if you create something based off an object from a tv show, video game, etc? Examples: Necklace pendent from Sora's keyblade (Kingdom Hearts) Necklace pendent from the necklace of a main character. (emperor's key from yugioh zexal)
In a word, Yes. The first thing you have to determine is what country the copyright owner is from, and then determine the copyright rules for that country. For example, most any American broadcaster will have paid the proper copyright fees before they transmit the program. That means that the original copyright laws extend to their broadcast of the program here in the US. Then, you need to examine the copyright rules for the appropriate country. Some laws require that you change more than 20% of the original before it becomes a new product. That means you can make something "similiar", but you can not advertise it "same as xxx", nor can you directly copy the original.
Unless you do a parody of it, or take it out of context, as part of the fair use laws. Also i have spoke to several people that create and sell movie objects form starwars, harry potter, dr who and several other show and they have never been contacted and told to stop making them. Fan art is often deliberately overlooked as accepted by the copyright holders as it promotes their shows. Usually they will not sue you if its going to cost them more for the lawyers than they will make in the lawsuit. plus it gets them bad publicity and a bad rap with the fans.
Would this be ok? Her is what it is based off of: http://24.media.tumblr.com/tumblr_m8giddfmSe1rdsudto1_500.jp g Here is what I made: http://jessp118.deviantart.com/art/yugioh-zexal-Emperor-s-ke y-367859958?q=gallery%3Ajessp118%2F17585610&qo=0
Personally, I don't think you'll have any problems... Now, if you were a factory pumping out thousands of these things, that might be a different story. All has to be taken in to context. BUT if you are contacted by someone with legitimate ownership of said item I would suggest strongly that you comply with their request to take it down from sale. You can still SHOW it, you just wouldn't be able to SELL it.