Here's an interesting concept for a modular structure, though I'm not sure where it fits within the marketplace of easy-to-assemble buildings: Camping? Disaster relief? Temporary housing? Living quarters for remote workers?
In any case, the $7,500 Quick Cabin is a 10x10 structure composed largely of modular rotomolded panels, each weighing 21 pounds.
"Our panels are rotationally molded from polyethylene, which is known for being highly puncture resistant, very robust, and UV resistant,. We use linear low density polyethylene (LLDPE), as we have found it to have the right mixture of strength and flexibility to guarantee the panels will always fit together and provide a strong, durable shelter for many years. The panels are foam-filled to add strength and insulation."
"To assemble the shelter, the panels are connected at the top, middle, and bottom with interlocking tabs using simple screws. A water tight edge gasket provides a seal between the panels. Each panel has a sturdy tie down ring on both the inside and outside."
"When not in use, the panels nest together for compact storage or shipping."
"The roof is made of a lightweight aluminum framework that slips together and is easy to assemble with just a screwdriver. The 3-layer roof cover consists of a heavy duty vinyl outside, lofty middle insulation layer, and protective lightweight inner membrane. The insulated cover quickly attaches to the frame with button snaps and pre-laced cord that engages hooks on the perimeter of the frame."
Of course, the Quick Cabin does assume you've laid a flat, level surface for it to rest on. Alternatively you can purchase the company's $1,300 UDECX modular floor, assuming you've got the skills to level it. I do think the potential difficulty, to the layperson, of leveling a 10x10 platform on uneven terrain does detract from the ease with which the walls can be erected (i.e. one part of the package does away with requiring building skills, whereas the other requires it).
Interestingly enough, the Quick Cabin's manufacturer, Quite Lite, started out in 2009 by using this modular system to create trailer housings.
One caveat: The company's webpage for the trailers read, at press time, "Sign up below to be one of the first to purchase these products in 2018."