I think Randy Charles is referring to Bob Essex's "MIDster" punching
machine.  For details, check out http://members.aol.com/midpunch/

This machine has a single hole punch which scans along the roll width
punching one hole at a time, then advancing the paper and punching
another row, etc.  Because it takes MIDI files and controls everything
through a PC it is very versatile.  Note spacing and paper advance are
all user controlled.

The plans include outline construction details for the mechanics and
electronics, and come with the software program.  I have a set but
haven't got round to actually building one yet.  I believe someone in
the USA (Ed Gaida?) made a "parallel" punching machine with a row of
punch heads mechanically operated but controlled by a PC, but I don't
think he published plans.

John Farmer
Archivist MBSGB