A hoop house is basically a metal frame covered with plastic or other all-weather material.

VOA: special.2009.12.22

The original Zeppelins were based on a rigid design in which separate gas-tight compartments were surrounded by a metal frame covered with a non-airtight fabric.

ECONOMIST: Pushing the envelope

Instead, Huibers and his team built the boat by welding together the metal hulls of 25 barges into a single frame, which was then covered with Scandinavian pine.

CNN: Dutchman builds replica Noah's Ark after flood dream

The tear-shaped frame of the Treetent is constructed from steel, covered in canvas and anchored to a tree trunk.

CNN: Sculptor creates treehouse-like tent