Did you know you can nest tools? If you drag the Circle icon and the Polygon icon into the same spot on your custom toolbar, SketchUp will create a fly-out menu (a small triangle in the corner). You click and hold to see the sibling tools. This is excellent for pairing Arc with 3-Point Arc.
Once the dialog box opens, you will see the available tools and commands listed. toolbar editor sketchup
Don't just throw every icon onto the screen. That defeats the purpose. Here are three professional strategies: Did you know you can nest tools