MM wrote:
If there is someone out there with a hot glue gun, what do you think
the chances are of it sticking the spine of a paperback book, e.g. 350
pages? I've looked at a number of paperbacks and they are all glued,
like the Argos catalogue, for example. The pages could be roughened at
the binding edge, held in a clamp of some sort (easy to make), and the
hot glue applied.

Another idea I had was to use iron-on edging strip.

I've done this with hot-melt glue, placed on a fabric strip, heated on a
hot plate so it goes into one gooey lump.

Place fabric strip on some foil - to stop it sticking to the hotplate.
Place clamped aligned book back on hot plate, along with the heated
fabric/glue.
Press down firmly while still on the hot plate for some seconds.
Slide foil off hot plate onto cold surface.
Allow to cool for several minutes.
Trim, and iron edges back.
Alternatively, there are progessional book-binders.