Some of you might be wondering what that little red button is for. It zeros out the Z axis. After you set the height of the laser you can press the red button. This let's the machine remember that setting. See first attachment.
What you can do with that is have the laser move in closer for another pass when cutting. In Lightburn you can program a layer to make more than one pass, and to move closer (or farther) on the second pass. This only works for line cuts. See second attachment.
The video of this in action is the third attachment.
If you use this feature please deselect it so as not to surprise the next user.