The linked idea was posted on behalf of my brother
Sturton, and a suggestion from [hippo] inspired this far
To the left (or right) of the trackpad on a MacBook,
should be two recesses which can accommodate the rolls
a small replaceable paper scroll, perhaps bearing
few feet of paper. A hinged bezel folds down,
the recessed rollers and framing the paper between
Under trackpad, mouse or key control, the scroll can
backward or forward between its limits.
Gadulka! You now have a space in which to make
sketches and other suchlike and, at the swipe of the
trackpad, the scroll can be advanced to reveal fresh
or rewound to locate old items.
Cunning software, coupled with a position encoder for
of the rollers, can even allow you index and retrieve
specified scroll positions.
Even cunnier software would make use of an inbuilt
linear scanner, allowing your sketches to be captured as
image files for further manipulation.