Solid, a frame or a shell structure.
Beaver dam?
Tent?
Human vs insect body?
Older vs modern race car?
Solid
Pile of similar materials into a shape
Mountains, coral reefs
Sand castles
Brick walls
Pyramids
Frame
Skeleton covered or filled with other materials
Modern homes with load bearing walls
Inexpensive
Weakness is the joints, type of material, anchoring