I have a model of a 6" diameter thin-wall tube, into which a couple of 3"-diameter tubes will be welded.  the axes of the smaller tubes will be perpendicular to the larger tube and are also skew: their axes will not intersect with the axis of the large tube. Moreover, one of the tubes will be distorted into an ellipse with a 2" minor axis, and the other is actually an elbow on a 4.5" bend radius.  The resulting cutouts in the large tube are of interest here.  I now have this shape modeled to my satisfaction, and would like to create a template I can print out and wrap around the large tube to identify where cuts need to be made.

Question: how can I "unwrap" this circular tube into a flat shape that I can use as a tape-on template for physically hacking/grinding those cutouts?   Sheet metal commands don't work here: those commands are expecting flat-surfaced shapes with sharp bends, not a smooth-round tube.

File is attached.