Pop rivets haven’t seen much use in the shop of late, but they always remain an option. You put one in the nosepiece of the tool, slide through a pre-drilled hole, and squeeze the handles. That action draws the rod and bead back to the tool, deforming the rivet to compress your materials together as the bead on the far side “pops” off. Can be handy, especially when you can’t access the other side of something easily.
This one was acquired at the tail end of the 1970s, for the not-insignificant sum of $25, or $100.54 today. You can pick up the equivalent tool from McMaster-Carr with delivery tomorrow for $31.25 plus shipping, whatever that tells you about the current state of the economy. Don’t read too much into it.
Note that the handle has also been etched with “Consumer Bargain,” which is cryptic and delightful. Clearly, this was a steal.