Repeating objects in scale is useful for easily creating a 'grid' of shapes with fine-tuned control.

CADtracker palette - Repeat
First create an object (with or without CADtools drawing tools). Select the object and enter values in the Repeat panel. Use the triangles next to Rows and Columns to set the direction of the repeat. Enter the number of rows and columns and spacing values in scale. Use the Between menu to apply the spacing between the edges or centers of the selected object. Click the Repeat button to repeat the selected objects.