Then I worked with Maf’j to design and make 3D printed prism and lens holders which slotted together and different height bases using Blender in order to find out the optimum lens and prism configuration. I did basic Blender tutorials and then during our sessions Maf’j helped me learn how to alter the sizes of the 3D models as a practical learning exercise. We concluded that it is hard in Blender to alter measurements easily and accurately. It would be better to use something like Solidworks, a design software tool used by engineers. Body Rocket, a start up making sensors for bicycles, offered the use of their engineer and software for a short time, once I have finalised the design and measurements.