During the design process of fusion reactors it is desirable to rapidly prototype different design concepts and assess their suitability against a range of high level requirements. This helps to narrow the design window and scope out potential designs which can undergo further more detailed analysis. The Paramak is an open-source tool that aims to provide automated parameter driven 3D CAD models for fusion reactor components and magnetic fusion reactors. The geometry produced is compatible with analysis workflows and this allows iterative automated model building and analysis to help steer the design optimisation process. The Paramak uses CadQuery and OCC to create the 3D CAD model. In this paper we demonstrate the use of the Paramak framework to create a few example reactor configurations including: a spherical reactor, a regular large radius tokamak and a compact submersion tank reactor. The models are not exact reproductions of any particular design but just reflective of different reactor designs that are available. Input parameters for the various reactors that the Paramak can generate generally fall into three categories. Which are continuous ranges such as blanket thickness, integer ranges such as number of toroidal field coils and categorical parameters such as type of divertor. The design tool facilitates parameter studies where users can investigate the impact of input design parameters on the reactor performance. The generation of output metrics from input parameters leads itself tothe use of data science and machine learning approaches to steer the design.