Openscad is a program and language for generating 3d models which can be used in games, CAD modeling, animation, or for printing with a 3D printer. It is a simple script based language system with an input window and the ability to render the script for viewing and further editing.
While controling or even slicing to gcode a 3d model for printing is probably not necissary on a phone scripting or editing a model and then being able to render and compile it seems like a good way to spend time waiting for an appointment or on the train.
A native client would be great with a toggle between the viewing window and the scripting window.
I think it could be popular, not sure if this would need openGL to speed rendering to a visible model or compiling code for output as a STL file.
http://www.openscad.org/