Anybody try building one? Seems to me that it would be about the
easiest project for homebuilt aviation, to build a backpack cage
with a motor and propeller.

Powered paragliding looks outrageous. They should fix the problem
of the pilot being slung/slammed into the ground at low altitudes.
Never seen people bounce like that. One guy refers to a type of
paragliding parachute as a "flat top", maybe that helps depending
on the drawbacks. Maybe they are still developing the best form of
powered paragliding parachute.

Anybody here do it yet? Anybody trying? Unfortunately, it probably
won't be me anytime soon. I would want to use electric power,
hopefully battery technology will improve rapidly.