I Think I have the same “widget” in mind, but I can’t find anything online that would match…
I think you’re on to something with that joiner link… the sheets are 1/16th of an inch, or .060″
I’m only seeing a U joint so far on that site…
“display building expert”? I think most people doing displays either have permanent joins, a rigid frame, or a single sheet cut to size…I could be wrong though, let me know if you can think of something else.