Remember these little handy dandy things?

[3clicks_Off]

Nothing personal but I'm thinking somebody was trying to electrocute you, and set a trap...
Metal to pull on metal (because glass breaks, ya know?), to break a circuit?
American Design wasn't that stupid in 1966, that came later .

They are not metal. Its like a thin pressboard or very dense paper. Similar to gasket material

 

[78Bronco]

I know a guy who claimed to have a friend that got shot in the leg this way! Supposedly he put the 22lr in as a fuse with the projectile facing the left and it got hot and went off. Claimed the round hit the e-brake bracket, causing it to come back and hit him in the leg. Never knew if it was true or not, but was always a good story to pass along.

 

[gh1950]

Changed many a glass fuse. One of the lessons of youth, when you put an amp on the 8 track and crank it up, the 5 amp fuse won't handle it.

not buying the fuse tool thing.

From the material you describe, sounds like a gasket for two bolts/stud, carb, fuel pump or some such.