Started work on the Engine mount this week. I had originally planned to let Jabiru USA design and make the engine mount but after 3 months and no mount, I decided to do it myself. The photo above shows the initial tube fitting fixture. These tubes were profiled using a little piece of free sofware called "Tubemiter". You can Google it or you can go here: www.ozhpv.org.au/shed/tubemiter.htm
The program only works for the intersection of 2 tubes. You just input the diameters of both tubes, wall thickness and angle of intersection. The program then provides a flat pattern which you print and wrap around the tube as a notching guide.
This is a poor man's version of CAD for tube mitering but it works very well. You are still responsible for determining tube length and correctly indexing the notches on each end of the tube.