Before the Undo Command, There Was the Electric Eraser
spectrum.ieee.org
spectrum.ieee.org
I'm kind of impressed at how those bits look pretty much identical to what you'd get today, and from the looks of it, they would fit in a modern Dremel rotary tool.
They definitely were worth it over “acoustic” erasers, but cost something like $70. The few times I got to use one spoiled me.
This is a reminder of so many things: Like chip and board "tape out" being done with actual tape on velum...