I use Visio for everything too, although I've been meaning to learn SketchUp to make 3D a little easier. Here are a few Visio drawings/edited photos from my current fiberglass trailer kit project, Visio is pretty capable:
Did this with Google/Trimble Sketch up. If you sign up with AutoDesk, you can get their software for free. I use Autodesk as well, but it has a steep learning curve.