Ive used Autodesk Inventor most days for a number of years and has always seemed pretty intuitive even at a beginners level. It can export to most of the 3D printing formats but can be quite pricy for a licence unless you stumble apon a cracked version on a torrent website..
Also seems popular for RC modelers and with a bit of practice.............
http://www.youtube.com/watch?v=DL15k-JZeOM