A structure-lining apparatus for lining one or more surfaces of a structure formed from curable material cast in a form, the apparatus comprising: a plurality of panels each panel extending in substantially orthogonal transverse and longitudinal directions, the panels connectable at their respective transverse edges (20, 22) in edge-to-edge connections to provide a structure-lining surface; a first panel of the plurality of panels comprising: a first connector component at a first transverse edge of the first panel; a second connector component, complementary to the first connector component, at a second transverse edge of the first panel; a third connector component, complementary to the first connector component, between the first and second transverse edges (20, 22) of the first panel; a fourth connector component, complementary to the first connector component, between and adjacent to the second and third connector components; a first breakaway component (38, 38') between the second connector component and the third connector component for shortening a transverse length of the first panel; a second breakaway component (38, 38') between the third connector component and the fourth connector component for shortening the transverse length of the first panel; and a second panel of the plurality of panels, the second panel edge-adjacent to the first panel and lockingly connectable in an edge-to-edge connection to the first panel by a first complementary connector component complementary and lockingly connectable to the first connector component of the first panel or a second complementary connector component complementary and lockingly connectable to the second, third and fourth connector components of the first panel; characterized in that a transverse spacing between the second connector component and the fourth connector component is different than a transverse spacing between the third connector component and the fourth connector component. a plurality of panels each panel extending in substantially orthogonal transverse and longitudinal directions, the panels connectable at their respective transverse edges (20, 22) in edge-to-edge connections to provide a structure-lining surface; a first panel of the plurality of panels comprising: a first connector component at a first transverse edge of the first panel; a second connector component, complementary to the first connector component, at a second transverse edge of the first panel; a third connector component, complementary to the first connector component, between the first and second transverse edges (20, 22) of the first panel; a fourth connector component, complementary to the first connector component, between and adjacent to the second and third connector components; a first breakaway component (38, 38') between the second connector component and the third connector component for shortening a transverse length of the first panel; a second breakaway component (38, 38') between the third connector component and the fourth connector component for shortening the transverse length of the first panel; and a first connector component at a first transverse edge of the first panel; a second connector component, complementary to the first connector component, at a second transverse edge of the first panel; a third connector component, complementary to the first connector component, between the first and second transverse edges (20, 22) of the first panel; a fourth connector component, complementary to the first connector component, between and adjacent to the second and third connector components; a first breakaway component (38, 38') between the second connector component and the third connector component for shortening a transverse length of the first panel; a second breakaway component (38, 38') between the third connector component and the fourth connector component for shortening the transverse length of the first panel; and a second panel of the plurality of panels, the second panel edge-adjacent to the first panel and lockingly connectable in an edge-to-edge connection to the first panel by a first complementary connector component complementary and lockingly connectable to the first connector component of the first panel or a second complementary connector component complementary and lockingly connectable to the second, third and fourth connector components of the first panel; characterized in that a transverse spacing between the second connector component and the fourth connector component is different than a transverse spacing between the third connector component and the fourth connector component.