Wouldn't the Hulk Fist-print in Skye's safehouse be considered a materials test?
Different box. The one on the hellicarrier was mostly made out of some transparent material, while the panelling in the cabin looked exactly like the isolation room on The Bus.
Besides, it's a bit unclear as to when and how that cabin was built. Coulson mentioned that Cap stayed there for a while after defrosting, so that would mean it was built some time prior to Avengers. By all accounts, aside from the Harlem incident Banner had been in the wind since the day after his first "episode". So it seems unlikely he built it with the co-operation of SHIELD and indeed the look of the thing seems similar enough to the one at the end of TIH that it's probably meant to be the same place, which raises the question exactly how he built it and with what resources? He was essentially homeless and destitute for years during that time.
I suppose it's possible Coulson was just lying about it being where Cap stayed, not wanting to freak Sky out be telling her he was putting her in a Hulk proof cage. That would allow for it to be built *after* the Battle of New York when Banner has access to Stark's resources
...or maybe it was a half truth in that Cap did stay there after helping Banner build it, but not *immediately* after waking up.