I downloaded this from another person here but I can't find the original post. Very simple and totally effective design, if anyone finds it let me know so I can mark it as a modification on the original.
I simply resized this to fit my iPhone 5S with my thin soft-shell case so I wouldn't have to remove my case when I used it, fits nice and snug.
All you need is a standard bolt to fit a tripod mount that slips in the hold in the model
iPhone5s_Tripod_Mount_for_CASE.stl | 11.9KB |