This isn't really game programming per se.
I just finished taking a graphics course at school. It was similar to autoCAD, but used Kutotek KeyCreator. I really don't like the program, but once I got the hang of it I could make some pretty sweet models quickly and efficiently.
My final project was to build a model of my guitar. It's a washburn classical guitar, nothing fancy. All of the measurements are pretty accurate, including the shape of the body and the curvature under the fingerboard. It actually got pretty difficult in many places. I'd say it took about 10 hours altogether to build the model (this includes taking measurements and screwups). The hardest part was taking measurements (I had to trace the profiles on graph paper and take sample points to approximate the shape).
It was also difficult assembling the final guitar, as it was built from three major pieces: the body, the fingerboard and the head. The places where the pieces met didn't want to 'go together,' and I had to find clever ways of blending them together.
I've attached two screenies.