Jaegers 6" f/10 "GJD" OTA Construction - The Main Tube (start of shallow groove cut)
 

Main tube being cut to proper size - 4. (Click to see an enlarged image.)

 
This image show the initial cuts around the circumference of the main tube along the card stock edge with my hacksaw. I will continue going around remainder of the tube with the shallow cut and progressively go deeper and deeper until the tube is cut thorough completely.