"Don't Text and Drive" iPhone 5S Holder/Mount for GPS
I made it 3cm longer than polygoo's design in order for the center of mass to be close to the middle of the iPhone when I attach it to my GPS holder.
Original iPhone holder design by Polygoo: http://www.thingiverse.com/thing:98693
Any Phone Car Dock by azzeloof: http://www.thingiverse.com/thing:48746
UPDATE: I created a version for the iPhone 6 Plus as well: http://www.thingiverse.com/thing:630137
And one for the iPhone 6: http://www.thingiverse.com/thing:659060