I would first do a lot of concept sketches, and also I would switch software. I would choose Alias|wavefront Studio or designer for this since Maya is more of an animation and film software and Studio is aimed at CAD - and you need CAD like software for designs.
Designs usually should be modeled in NURBS Degree 5 - 7 surfaces and Studio excells in this area. Also Studio exports directly for production in various formats like IGES, STL, PRO/E etc.
Create the concept sketches
model the object
export for production
ofcasue you can break down each point in smaller stages with rendering, texturing etc.. but that would basicly cover it..
Senior 3D Artist,
Maya Software Manager & Maya Instructor
LEGO Systems A/S