One of the new-to-AutoCAD-LT commands in AutoCAD LT 2011 is the Sketch command. Previously available only in AutoCAD, Sketch received a makeover in this release (in both AutoCAD and LT) and is now easier to use and more flexible.
By default, Sketch is only available from the command line, but you can create a button for it if you want. Once you start it, left-click to start a sketch, then – without clicking – drag the cursor along the path that you want. Left-click again to end that sketch path, and left-click once more to start a new path. When you’re finished, press Enter to record the sketch.
The green color you see while the command is active has nothing to do with the current layer or color – all sketches are green while they’re being created.
Within the Sketch command, you have three options for controlling a sketch’s appearance and behavior: Type, Increment, and Tolerance.
Type controls what kind of objects are created when you finish the sketch. Your choices are Lines, Polylines, and Splines. (Unless you really want a headache or two, don’t choose lines.)
Increment determines the size of individual sketch segments for polylines and lines, or how far you have to move your mouse before a new segment is drawn. Smaller numbers mean smoother sketches, bigger increments lead to rougher sketches. What increment you choose will depend on the scale of your drawing and the purpose of the sketch.
Tolerance is only relevant if you’ve chosen Spline as your object type. It controls how close the finished sketch comes to the points your cursor passed through. Tolerance can be set to any value between 0 and 1 (inclusive), where 0 means the spline fits perfectly to the mouse path (potentially a very rough line) and 1 provides the smoothest curves (potentially not very close to where your mouse went). The default value is 0.5, and you can experiment to see which value works best for your sketches.
In the image below, the sketch on the left had a tolerance of 0.5, the one in the middle had a tolerance of 0, and the one on the right had a tolerance of 1.