I did this quick design of a camera mount for a Felix 3.0 Printer. This version is a two piece design that mounts from the other side, making it easier to control the camera.
Velcro works great for smart phones. The holes in the sides of the spherical joint are sized for a 1/4-20 tap. The holes in the mount are #8 flathead sheet metal screws. Use a #6 for the top one, the hole in the mating part is small.
I use the print cone to slow down the printing so the small top layers have some time to cool.
This is a time lapse that I made with the iPhone 4S using the Mk I mount. The need for better control and position of the camera is evident.