What we call conventional or "stick-built" RV construction starts with a (usually) steel chassis. The walls and ceiling are framed with wood, steel, or aluminum and covered with some kind of exterior skin (commonly aluminum or fiberglass sheets).
All-molded construction starts with a similar chassis, but the entire cabin- walls, ceiling, and sometimes the floor as well- is formed by laying up fiberglass in a mold. Typically two sections (upper and lower or left and right) are then bonded together so that the whole cabin becomes a single, self-supporting unit. There is no framework inside the walls, similar to a fiberglass truck topper. Inside some are finished out with molded fiberglass cabinetry as well; others have conventional wood cabinetry.
You can see a molded fiberglass trailer being put together in the promotional video on the Scamp website
(starting at about 7:00).
Advantages of all-molded fiberglass construction include (1) lack of exterior seams, (2) light weight
, (3) fewer leaks
, (4) aerodynamic shape.
Hope that helps a little to clarify what makes our "egg trailers" different!