Danny, kerfing only works on wood and a few other materials AFAIK;
plexiglass has the wrong plastic/elasticity curve for that (...he
says, 20 years after his last mech engineering course...). That said,
I grew up watching my uncle do incredible bends in plexiglass with a
carefully applied blowtorch. So the design's from the link are
doable...you're just not going to be able to achieve it with
mechanical bends.
--
Mark Turnage