Is there a reasonable limit to the distance over which a piece of aluminum might be imported to Gardner/Niku Island? Canton Island has already been suggested, but what about more distant places? There were a lot of documented wrecks all over the Pacific, but obviously not all were within "reasonable" distance from Gardner to consider for importation.
I can think of 3 different importation scenarios - 1) Gardner Islanders visiting family on other islands or mainland and bringing pieces back home, 2) Supply ships or other visitors bringing a variety of stuff for sale or trade, and 3) Military personnel bringing stuff that gets left with the islanders, either as gifts or abandoned in place.
(There's a 4th scenario - aircraft pieces arrived on the island by air, in the form of a complete flying aircraft, while the island was unpopulated before the war.) Each of these scenarios might imply a different importation radius. Military personnel for one example might bring spare parts from the US (or Britain, Australia, or even Japan, if any of them visited the island before, during or after the war). The USCG Loran station on Gardner was resupplied occasionally by aircraft, which might have been repaired on-site for example, leaving the left over scraps. The type of material and rivets would (presumably) be unique to US military aircraft and easily distinguished from 2-2-V-1, wouldn't it?
What is known about islanders likely family visits? Emily Sikuli was living in Fiji when TIGHAR interviewed her, and went to school in Tarawa, but never returned to Gardner. What route did she take to get to Tarawa and Fiji, and were those trade routes that might have also been a way for metal scrap to find its way back to Gardner?
Would US, British or Japanese pre-war flying boats have used similar metal/rivets? They were operating in the South- and Western-Pacific as early as 1935 or 36. Many of them got shot up early in the war, especially in Australia, and might have been salvaged. Is Australia too far away to consider as a source?
By what I understand of the material involved in 2-2-V-1 (vintage - distinctly pre-WWII metal as-marked and by presence of brazier rivet) this part did not come from just any airplane, but something of the L10's time and make-up - and something distinctly of American technology. That limits likely sources to domestic 'other than' war types reliably well, IMO. Yes, there were 'other types' operating where you note - New Zealand, Australia, New Ginea, etc. - all a long way from Niku.
So what are odds of scrap as we see making its way from such places to Gardner / Niku? Did islanders who turned up there have relatives in places where those operations were going on, and did they have access to airfield (or crash) sites where scrap could be harvested? If they did, did they come and go in such manner so as to obtain odds and ends to take back for trade and to work into useful things? Seems far-fetched to me as I undersand the people who inhabited Niku: they weren't exactly highly-mobile enough to reach such places or their circumstances wouldn't have put them on Niku.
Did someone export such stuff in hopes of promoting trade? Somehow the notion of westerners thinking to do that - glean odds and ends out of junkpiles to stow away for eventual trade doesn't seem likely ("oh what a nice torn piece of dural - think what a nice comb some islander could make for that if I take it there in hopes of gaining favor...").
We can't know for sure, of course - but this stuff looks like it was opportunistically gotten from the field - off of damanged goods. Why the diversity, of which some obviously came from a non-L10 type (like the PBY bookcase)? Not easy to answer - stuff other than 2-2-V-1 generally doesn't appear to have come from Niku because we don't know of any potential donor craft that would have borne that stuff by definition. The island was visited prior to and during WWII by some known types, with no accidents known: Colorado's biplanes - no landing; a Walrus overflight - British, different construction, no accident; seaplane visits to Loran station - no accidents known. No real opportunity to glean such stuff from those birds.
We know there were military losses on other islands in the area - DC-3, PBY, etc. - all potential donors for some things we see, but not good sources for what we observe in 2-2-V-1 (vintage of metal and fastener don't add up to those types). So back to 'did someone obtain this off of a civilian pre-WWII type elsewhere - south to west Pacific - and import'? Can someone show me why it is believeable that islanders had that kind of reach for such stuff? We're talking 2000 miles distant, and then either access to a crash or an airfield scrap bin - fairly narrow case at the end of a long journey.
I submit that this stuff was of more local and easily-opportunistic origin - that the military-like stuff could easily have come from neighboring islands, wherever there was a crash that produced donated stuff. So where, nearby then, was the pre-WWII lightly-built ('cabin class twin' is a good description) that bore external pre-war metal stampings on alclad that was fastened with light no. 3 brazier rivets? If a donor for that was found on another island, wouldn't we likely know of it, like we do the DC-3 and PBY, etc.? I submit 'probably so' - but we don't.
So where was the donor? We have anecdotal accounts of a wreck at Niku - not anything firm but a potential source; more than that, we have a distinct piece of aviation repair history that by markings and a remaining fastener speaks volumes as to the presence of 'something very much like a Lockheed L10' having been about. We're back to a very narrow, pointed case IMO - not too many donor craft in the area, and where is the mostly likely spot for an L10 to have passed with far too little notice, as other history and circumstances suggest?
I'm not sure the public, or even many aviation specialists for that matter, really appreciate how unique 2-2-V-1 is as to how the stars cross on its markings and fasteners, right down to a grip length indicated on the surviving brazier rivet that it was tacked onto .060" of underlying structure, consistent with what we see in the museum shots of the L10 belly. We have a very unique piece of aviation metal on our hands - found on Niku, and with no really good explanation for it finding its way there short of having flown in on an intact ship that never left that way. Further, the way it broke away - whether in one explosive action or by being 'worried' at by the sea and finished by man's hand, etc. we do see evidence of it suffering fatiguing trauma that is consistent with mother nature's hand in the surf: something fretted with this metal over time before it got to where it is, and it was not lacking in some violence to have come from the parent structure in the form that we see today.