Posted 12 January 2011 - 10:37 PM
Photo editing and CAD Modeling are not remotely similar. I am a Drafter/Machinist and in school for Mechanical Engineering.
Photo editing I have done rarely like throwing some text onto photos and the front runners in the free world are GIMP, and Paint.NET. Personally I prefer Paint.NET because the interface is very familiar to the Windows user.
For 3D Modeling there is a free program called Blender which works well for ART and only ART. If you want to get into traditional CAD such as AutoCAD or more modern parametric software such as Solidworks then the answer is that there is no free software and with no training you need to take a class to use the programs well. Also keep in mind CAD is designed for engineering and not drawing pretty pictures, they are designed with engineering standards and concepts in mind.
AMD Phenom II X6 2.8ghz
8GB DDR3 RAM
XFX ATI Radeon HD6850 1 GB DDR5, 26" Widescreen HDMI
500GB + 80GB HDD
Windows 7 Pro, Mozilla Firefox, AutoCAD 2011, Solidworks 2009