I have been involved in a hobby project for the past four years or so using SketchUp to create a high-fidelity model of an actual object - the Viking '75 Mars Lander spacecraft. Two were launched in 1975 to Mars and both landed successfully in 1976. Here is a video I created last year about the process I use to create the digital 3D model. Here is an album of 2D images of the model, as a work-in-progress.
I am trying to faithfully re-create a detailed model with fairly high accuracy (on the order of a millimeter or two wherever possible). This makes the creation process very slow (for me anyway). After somewhere between 1000 and 1500 hours, it’s less than half done. 
As mentioned in the video I’ve had the great fortune to visit a number of remaining Viking test hardware components in museums and captured over 1000 direct measurements (here are some examples), and I’ve taken about 3500 detailed photographs that I use for reference (here are some examples) to estimate dimensions where needed. I also acquired a set of assembly blueprints that have been very helpful for the core spacecraft body.
Here is a topic in this forum’s gallery section on the spacecraft components I am currently modeling.