A sketch plugin is a tool that allows the UX designer to quickly mock up Salesforce user interface experiences using the Lightning Design System (SLDS) resources, such as base components, tokens, and design patterns. The sketch plugin is a free plugin for Sketch, a design toolkit that helps create wireframes, mockups, sample screens, and more. With the sketch plugin, the designer can search and drag the prebuilt components from the plugin into the canvas, and export the mockups as pdf, jpeg, or png files. The sketch plugin also supports synonyms and variants for the components, making it easier to find and use the desired elements. The sketch plugin can be downloaded from the SLDS website1 or from the AppExchange2. References:

[Create Quick Salesforce UI Mockups: Lightning Design System Plugin for Sketch]1

[Lightning Design System Sketch Plugin]2