I think that 50VDC will be reasonably safe so long as it's
indoors, in a dry area, and the voltage is not referenced to
earth ground. Put whatever protection you can around the area
to reduce the chance of people grabbing things.

That said, I think there's a significant chance of injury
due to *thermal* burns. That Nitinol wire gets pretty hot,
as I recall, and there should be enough power dissipated to
give somebody a nasty burn. You're more likely to have trouble
due to this than from electric shock. Remember McDonald's
and the infamous 'hot coffee' lawsuit!

Why would you want art lovers to touch this thing anyway? Those
wires aren't very rugged, and the first ham-handed six-year-old
that gets close will destroy it in seconds. And probably think
it's funny, too.......

forbesm@peak.org   KC7LZD
Mark G. Forbes
"Never ascribe to malice that which can be blamed on the engineer."