This chapter introduces the rendering library, NanoVG, used to draw user-defined lines and shapes and to render scalable-vector graphics files (SVG), suggests how to customize available classes to get custom knobs and text labels. It proposes a variation of the Modal Synthesis plugin that adds an interactive graphical user interface element for sound generation. The draw method is called periodically, and will update the display and the mass information, eventually calling the new impact method of AModal if the mass has touched the ground. Text labels should be placed in the panel background SVG file, as already discussed. However, at times, it may be useful to add special text widgets to display informative content.