The pneumatic Auto-typist was popular right into the '60s, and was
used well into the 1970s, I believe.  It used a rotary pump like a
reproducing piano, but the body was cast metal.  The 4 bellows are
leather covered.

These are occasionally available today and make good pumps for
build-ups.  The main nipple has to be enlarged, though, as it's only
about 1/2 inch.  My friend John Berry told me how he bought out an
Auto-typist repair shop and got a number of these units.  The roll
frames look like they came from a nickelodeon, too.

Philip Jamison
West Chester, PA