As usual, I find that I was way ahead of my time.  Quite some time ago I made a similar gadget, but out of soft plastic, so that it was fairly easy to collapse and fold up and carry in the field, even backpacking.  I used it to change lenses without dust contamination.  Problem was, that it took too long and you don't want to be messing with such a thing while the light is best and rapidly fleeting.  Uh, anyone want to buy mine? Same deal as the ebay thing; no guarantees, you buy, you try, you're stuck.

Yeah, but my unit could double as an ultra high-power and efficient recreational pharmaceutical inhalation station.  You shoulda seen the pictures I posted.  Exotic dope inhalation device was the first thing folks thought of.  Genius is never recognized in it's own time.  :p
Uh, sometimes not later either.  I long ago realized I'm neither ahead of my time nor behind.  I'm substantially displaced SIDEWAYS in time.

Check it out!

But the e-bay unit can double as biohazard workstation.:-)