Some enterprising Maker has figured out that you can generate 3D printable files from an iPhone app (iTracer) that costs less than $3. I always knew that this would eventually become possible but the inexpensive ecosystem that is the iPhone App Store has finally proven it to be true.
As it turns out there is a 3D CAD modeller on the iPhone caller iTracer programmed by Fabio Policarpo, and it is actually quite good. It’s no Solidworks but it is an interesting first attempt at simple 3D modelling on an iPhone, there is even a Ray tracing and export options.
Considering that the program exports fairly standard 3DS files you should be able to print on a big range of 3D printers from Makerbot to Z-Corp.