This car phone mount can be customized to accommodate a wide selection of phones and instances. It clips onto the port using the really nice vent clip made by jasper_pues. The concept was inspired by the gcode developed by diametric.
Update Apr 20, 2015: Unfortunately I had to remove the rounded edges because of problem with the customerizer.
Use the customizer to spend the size of your phone or case. Add one millimeter into the sizes to be sure that you can slide it in and out easily. The port clip is printed separately and must be glued into the slot when the prints are done. A couple of drops of superglue works great. The clip prints stronger if you put it on it's side, if you do you will need support, otherwise, no support should be required. You might have to clip off a series or two out of the mounting slot based on how well you printer does bridging. Obviously, your printer will have to be well calibrated to print this the appropriate size.