This paper presents a design tool for Induction Machines, Permanent Magnet Synchronous Machines, Externally Excited Synchronous Machines and Switched Reluctance Machines. This software, based on Modelica language, is able to provide full dimensioning (cross and axial section measures) and operation characteristics according to mechanical and electrical requirements set as inputs. The tool is able to perform error handling, which informs a designer about unfeasible designs and gives clues about the possible errors. Both aspects of the tool GUI and scripts provide help files and code explanation in order to re-use the tool and improve library's functionalities.