Here is a more organized presentation. See PDF attached with annotations added.
The gasket artifacts relationship to the clip artifacts. The gasket and clips were found in the same area.
A gasket used for its intended use should be flattened evenly, yet the artifacts are not. A gasket protecting threads from being cut by a thin plate could deform the gasket un-evenly. See picture of un evenly deformed gasket and fan pattern with circular ring in the enlarged photo.
The clip relationship to the thread pattern If the first threads filled up the hole, then forcing the remaining threads in behind them could gouge the rim of the hole behind the threads. An awl may have been needed to open the hole wider in the leather. An awl or heavy needle could cause the gouging seen on the artifact. See picture of clip for gouging than occurs behind where the first threads would be. Note there are no rotation marks at the smaller hole, just at the one with the screw.
Regarding if the box in the picture is “The sextant box”“Mr. Gatty thinks that the box is an English one of some age and judges that it was used latterly merely as a
receptacle”
That later use could have been a receptacle for tools
before the flight. The box was described as having dovetail joints. The box in the picture has what appears to be dovetail joints. An aircraft mechanic could have made a tool box from an old sextant box or “The sextant box” was taken out to lighten the tail.
Possible “smoking gun”? The artifact is not a machine manufactured item. The holes are not centered, the cuts un even. This artifact is a one of a kind item
The clip in the picture already looks bent out and has a similar size and shape to the artifact. The picture is only 96dpi. If what looks like teeth could be enhanced, they could serve as an identifying "bar code" if they match the hand cut teeth of the artifact. Also the gouge marks could identify the clip in the photo as the artifact found
I'm not sure of the scale of the gaskets. I only have the picture Irv took of them from a presentation at DC. I attached a jpg crop of the gasket since making a pdf presentation from the jpg made some distortions.
Please click on the PDF below. Not just the jpg