Autodesk Inventor is the ultimate software program for 3D models of all your mechanical engineering designs. What's special about Autodesk Inventor is that the focus is on how the design works, rather than on the modelling process.
Inventor 2016 lets you draw using several centrelines and change your sketch to a frame, linkage, sheet-metal or other structure with a single click. You can also cost out and optimise designs. This 2016 version of Autodesk comes with plenty of extras, including: new electrical engineering workflows, new freeform tools and a new 3D printing module.
When you purchase a licence for Autodesk Inventor Professional 2018, you also have the right to use the 2016 version. This is the only way, in the new licensing structure, to "buy" Inventor 2016 (further information on licensing).