I am looking for some software to create 2D designs with a high degree of accuracy. To lend some background, what I've been doing is drawing diagrams in Autodesk Inventor, creating 1mm extrusions of the parts I'm interested in, transferring them to top down diagrams and then exporting them to GIMP to add colour and apply finishing touches. As I'm sure you can guess, it's an arduous process, but I've not found any other software with the extensive 2D manipulation capabilities provided by Inventor. It allows me to apply specific constraints, manipulate sizes of graphics to a tiny degree and use their extensive range of tools and tricks to get the exact designs I'm looking for.
But to cut down the process, I'm looking for some software that can allow me to still do that kind of thing, but without the emphasis on the 3D design elements of Inventor. Ideally, letting me still create very accurate and fine-grain designs, but with added tools like area fill or changing line colour, and saving straight to image files. Does anyone have any recommendations?