Get Trimble Sketchup and start drawing, you'll be surprised how easy it is. Converting Sketchup to STL format for Shapeways (almost all 3D printing systems use this format, it's the same as I created for my Predator parts) is easy too, they even have a tutorial for it. I'd recommend creating the models in Sketchup at say 100 times actual size, as it doesn't like drawing objects smaller than 1mm so for fine detail work you need to scale up. Scaling it back in one of the conversion tools should get you a print with fine details, but it's worth checking the Shapeways
FAQs to see what their print resolution is like, no point drawing details smaller than the printer can handle.
Easiest way to start with Sketchup is to import a PNG flat image with the design you want, and then trace it using lines and arcs. Once you've got your initial flat shape use the extrude tool to give it depth, and you've done the icons to glue onto doors. Shoulder pads will be a bit harder as they need to be curved and that can be fiddly, but you could try getting them printed flat and very thin and hopefully when you use a liquid poly glue it'll soften the plastic and allow it to bend.