I liked entomophile's remix of my earlier tripod mount. I had some M5x45 hex head screws lying around from another project, so I decided to make use of one for another tripod mount. Sized for an iPhone 6, may work with other phones. Fusion 360 file provided if you want to resize. See instructions for some notes on printing.
Update: v2 adds a side mount nut option for portrait mode.
The main base file can be printed entirely without supports. It makes use of some modeling tricks that assume a .20 mm layer height. Screw holes are purposely blocked with a single layer membrane to allow them to print without support; after printing, just drill through those. You can also just pick out the filament with some tweezers easily enough.
Files are oriented as they came out of the modeler, so reorient them for printing.
Knob should be printed top side down with support.
Requires an M5x45 screw, an M5 nut which goes into the nut trap in the middle, and a 1/4-20 nut for a tripod bolt which should be glued into the exterior nut-shaped hole.