Sony T3 blurb:
A slimmer, lighter Reader™ ...With a comfortable
protective snap cover..
...Slip it in and out of your jacket... This is the Reader that’s as thin, light and versatile as your everyday paperback.....
..Ultra lightweight 200g (including cover)...
my italics - did not do a very good job of protecting mine
and the suggestion that you walk about with it slipped inside your jacket noes not equate to
treat it like a very fragile piece of glass!
if your top design aim is
ultra lightweight then robustness has to be less important.