A structure for forming a linear shaped charge, the structure at least partly fillable with detonating cord (4a, 4b, 6a, 6b) by a user to form the linear shaped charge, and the structure comprising: a body (2, 102) comprising a foam material; a first cavity (18, 118) comprising a first flat surface (26, 126); a second cavity (20, 120) comprising a second flat surface (28, 128), wherein the first flat surface and the second flat surface converge towards an apex; and i) a first liner (8, 108), a first portion of the first liner (8, 108) corresponding to the first flat surface and a second portion of the first liner corresponding to the second flat surface, wherein the first cavity and the second cavity are each configured to receive detonating cord such that the first portion of the first liner (8, 108) is adjacent to or in contact with detonating cord in the first cavity, and the second portion of the first liner is adjacent to or in contact with detonating cord in the second cavity; or ii) a first liner (8, 108) and a second liner (9, 109), the first liner (8, 108) corresponding to the first flat surface and the second liner (9, 109) corresponding to the second flat surface, wherein the first cavity and the second cavity are each configured to receive detonating cord such that the first liner is adjacent to or in contact with detonating cord in the first cavity and the second liner is adjacent to or in contact with detonating cord in the second cavity. a body (2, 102) comprising a foam material; a first cavity (18, 118) comprising a first flat surface (26, 126); a second cavity (20, 120) comprising a second flat surface (28, 128), wherein the first flat surface and the second flat surface converge towards an apex; and i) a first liner (8, 108), a first portion of the first liner (8, 108) corresponding to the first flat surface and a second portion of the first liner corresponding to the second flat surface, wherein the first cavity and the second cavity are each configured to receive detonating cord such that the first portion of the first liner (8, 108) is adjacent to or in contact with detonating cord in the first cavity, and the second portion of the first liner is adjacent to or in contact with detonating cord in the second cavity; or ii) a first liner (8, 108) and a second liner (9, 109), the first liner (8, 108) corresponding to the first flat surface and the second liner (9, 109) corresponding to the second flat surface, wherein the first cavity and the second cavity are each configured to receive detonating cord such that the first liner is adjacent to or in contact with detonating cord in the first cavity and the second liner is adjacent to or in contact with detonating cord in the second cavity. i) a first liner (8, 108), a first portion of the first liner (8, 108) corresponding to the first flat surface and a second portion of the first liner corresponding to the second flat surface, wherein the first cavity and the second cavity are each configured to receive detonating cord such that the first portion of the first liner (8, 108) is adjacent to or in contact with detonating cord in the first cavity, and the second portion of the first liner is adjacent to or in contact with detonating cord in the second cavity; or ii) a first liner (8, 108) and a second liner (9, 109), the first liner (8, 108) corresponding to the first flat surface and the second liner (9, 109) corresponding to the second flat surface, wherein the first cavity and the second cavity are each configured to receive detonating cord such that the first liner is adjacent to or in contact with detonating cord in the first cavity and the second liner is adjacent to or in contact with detonating cord in the second cavity.