This is a parametric Smartphone holder for your car. The basic size can be adjusted using OpenSCAD, so you can create a custom holder for your phone depending on the model and your protection case.
When you have created the basic holder you might also want to add holes to press buttons, reach the charging or headphone plug or for the speaker. If you align the holes at a good place you can also use them to remove your phone easily from the holder.
There a two parametric functions available which let you create long, closed holes with rounded corners (for the speaker) or open holes with rounded corners (for charging and headphone plug, buttons, to remove phone). The size of each hole can be specified by modifying the functions paramerers.
There is also a function to create custom holes in the bottom of the case to screw it into your car. I mounted it on the mobile phone console of a Smart Roadster.
Currently I don't have a picture of the phone inserted into the holder. The main problem was, that I didn't have a camera with me, but I can tell you that the iPhone (with case) matches the holder perfectly. It is a bit tight, so the phone can't get out on Germanys bad streets ;)
Feel free to modify this holder. It is currently designed for an iPhone 6s with a Spigen case (http://www.amazon.de/Spigen-Schutzh%C3%BClle-iPhone-Liquid-Luftpolster-Technologie/dp/B0141U0X6K/). If you modify this thing, please load it up to thingiverse and mark that it is a remix. This way we can get a big library of prepared smartphone holders for different smartphones!
I printed this thing with an infill of 25% and a resolution of 0.1mm. Support and rafts aren't required. I think you could increase the resolution, I just wanted a nice looking surface, so I decided for a high resolution.
This thing was designed using OpenSCAD. This way it allows to be modified for other smartphones. In future you could buy a new smartphone, customize this holder and mount the new version again in your car.
Don't use PLA! It bent just after the first sun in the spring. Instead use ABS or better PETG