Text Box: I have developed a hollowing tool based on proven research.  It is fairly easy to make with basic shop equipment and a little welding.  Written instructions on how to build it are below.  I have also developed a laser guiding tool for the rig which requires more welding and a very special laser sight (available at Academy Sports) I'll provide details on that as they can be developed.   For a materials list, and direction, click here. . Some photos of the tool with different cutters inserted.   This is the laser sight you will need for this rig Here's a sketchup of the laser with dimensions. You can make it with stuff you buy at HD or Lowes.  Here's a link to some of the tools which can be held in the tool for hollowing.