The Hourglass Tower in the 2013 National Jamboree Pioneering Area was set up as one of four tower displays.
“The Hourglass Tower is something of a classic for Scout pioneering. John Sweet’s excellent book Scout Pioneering describes it, and since then many Scout troops have built one.” (Read: Erecting an Hourglass Tower in Ropes and Poles.)
“The tower is constructed from two large pyramids interlocked together.” (Read: Hourglass Tower in Poneering Made Easy.)
As an interesting side note: by employing rope tackles in each of the lines marrying the two tripods, effectively tightening the connections was very easy to accomplish.