My father had done alot at Stanley Works many years ago. One area the made those, and their contact/ overseer would let them take samples of different things and show them different operations and things.
One of the samples he brought home was a pocket full of those bubbles.... But they were in their vials.
That was back when they manufactured here in New Britain.
They would trade in their tape measures , which were well worn. For new ones. R & D wanted them from the real world. He used to repair his tapes back in the day. They gave new replacement blades as well.
But yeah those bubbles vials is what came to mind. He kept them on his benchtop for years. I wouldn't be surprised if has them squirreled away someplace. He turned 93 last May.