Autodesk offers an LT suite that bundles Inventor 2015 and AutoCAD 2015, the affordably priced versions of the two main programs in which you can move between 3D-CAD mechanical engineering designs and 2D-CAD drawings. 

The AutoCAD Inventor LT Suite now makes parametric modelling cost-effective and practical. Importing PDF files, centerpoints, collaborating with colleagues or customers are just a few of the things you can do. Increase your productivity with the AutoCAD Inventor LT Suite.

When you purchase a licence for Autodesk AutoCAD Inventor LT Suite 2018, you also have the right to use the 2015 version. This is the only way, in the new licensing structure, to "buy" AutoCAD Inventor  LT Suite 2015 (further information on licensing).