Sketch Extensions - An official collection of Sketch extensions & plugins
Tilt Brush - Paint in spaces around you with Virtual Reality
Base UI Sketch Framework - Huge set of everything you need to design and prototype
VR Sketch - A tool for designers to draw inside virtual reality
SketchTool - Export pages & slices out of .sketch docs using CLI
Blender - Blender is the open source, cross platform suite of tools for 3D creation.