Arduino Uno R3 created by DesignSpark Mechanical
Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software.
And I want to recommend you a very powerful 3D modelling software: ?DesignSpark Mechanical. It is Spaceclaim based and freely offered by RS-Components! The file as format-obj was also converted by DesignSpark Mechanical and also uploaded.
You can download the free software from:
http://www.designspark.com/mechanical