This paper presents an open-source object-oriented MATLAB toolkit for control system design and system simulation. The objective of the toolkit is to reduce the time required for the design and validation of a control architecture while at the same time increasing the reliability, modularity, and reusability of each of its components and fostering collaborative design and sharing of the developed components. To reduce the development time, a set of ready-to-use functions that are commonly required by control design processes is provided, such as automatic generation of Extended Kalman Filters, discretization, and many others. Moreover, we define a set of common interfaces to integrate the different standard components. The toolkit is introduced by means of a practical example, starting from the modeling of a planar Unmanned Aerial Vehicle, implementation of a two state-feedback controllers (one simple but nonlinear and another more complex using a Model Predictive Control approach), automatic generation of a state estimator, simulation, and remote network control over a Local Area Network.