This is the fourth in a series of videos about how to build an RGB colour mixer using Visual Basic.NET. This series covers the use of the VB.NET graphics object, along with a range of related objects and their methods for drawing and filling shapes on a Windows Form. This particular video includes step by step instructions on how to use the GraphicsPath object in your code. The GraphicsPath object allows you to draw complex shapes consisting of sequences of lines and basic shapes such as rectangles and circles. More importantly for the purposes of the VB.NET colour mixing application, the graphics path can be used to create a new region object, and it is possible to obtain the intersection of two regions. This provides a mechanism by which you can easily find the intersection of two circles.