123D is free 3D CAD software to help you quickly give shape to your idea, explore it, and most importantly, make it. Design precise and makeable objects using smart tools that let you start with simple shapes and then edit and then tweak them into more complex designs.
Windows 7 (32-bit or 64-bit), Windows Vista® (32-bit or 64-bit), Windows® XP Professional or Home Edition (SP3), or Windows XP Professional x64 Edition (SP2), Windows Server 2008.
Intel® Pentium® 4 or AMD Athlon® 64 or later with 2 GHz or faster processor; or compatible
1+ GB RAM (512 MB minimum)
1.5+ GB free disk space (for installation)
Direct3D® 9 or 10 graphics support with 64+ MB