We worked with Alexander Pelikan last year with his Machine's Perception project. This year Alex came up with 3D printed doorhandles for a project he did with TNO (a dutch research institute). The designs are based on the perception of the 3D scanner and I think they make lovely objects for in the home. We tried to 3D print one in Stainless Steel for him but sadly the model he wanted to print was too thin. We'll try again soon. You can check out a lot of Alex's work on his website PeliDesign.
Design door handles and door knobs are expensive. You could make a 3D printed steel door handle plus backing for about $250-350. That is a lot of money but comparable design label doorhandles are much more expensive still.