N967MD

Interesting term, referring to the shape of the end of a pipe joining other(s)... technically called a saddle joint, but usually referred to as a fish mouth because of the appearance.
The goal is to end up with a close fitting joint between the 2 or multiple tubes...
This joint won't get welded, there is a trim piece that goes around the door opening that will cover this with a rivet into the stringer... but I wanted a nice fit anyway.

And while it's hard to see a black tube structure amidst all this stuff, here she sits with both side and bottom stringers in place.