A method of forming a tool for producing a panel spanning a discontinuity, the discontinuity being defined between a first segment and a second segment, and having a lateral displacement and a longitudinal displacement, the method comprising: applying a first build ply to an initial ply, the initial ply partially co-extending with the first segment and at least spanning the lateral displacement, the first build ply having a leading edge and defining a thickness, and the first build ply being applied to the initial ply such that the leading edge thereof is proximal to the first segment; applying a second build ply to the first build ply, the second build ply having a leading edge and defining a thickness, and the second build ply being applied to the first build ply such that the leading edge thereof is laterally displaced toward the second segment from the leading edge of the first build ply; applying successive build plies to build on the second build ply, the successive build plies including a medial section of build plies and a last build ply, such that the last build ply partially co-extends with the second segment, each of the successive build plies having a leading edge and defining a thickness, and being applied to a previous build ply such that the leading edge thereof is coincident with, or is laterally displaced toward the second segment from, the leading edge of the previous build ply, the lateral displacement between leading edges of the successive build ply and the previous build ply, in relation to the thickness of the successive build ply, defining a ply drop ratio, the ply drop ratio decreasing up to the medial section and increasing from the medial section to the last build ply such that a surface defined by the last build ply, the first build ply, and the leading edges of the build plies therebetween define a substantially curvature-continuous surface profile extending between the first segment and the second segment; and prior to applying the successive build plies, determining a shape of the substantially curvature-continuous surface profile based on an adjusted ply drop ratio for at least a portion of the successive build plies, wherein the adjusted ply drop ratio is directly proportional to a linear ply drop ratio, and inversely proportional to a softness factor and a ply drop number, the softness factor ranging from 0 to 1, the ply drop number being the number of the build ply between the first build ply and the last build ply. applying a first build ply to an initial ply, the initial ply partially co-extending with the first segment and at least spanning the lateral displacement, the first build ply having a leading edge and defining a thickness, and the first build ply being applied to the initial ply such that the leading edge thereof is proximal to the first segment; applying a second build ply to the first build ply, the second build ply having a leading edge and defining a thickness, and the second build ply being applied to the first build ply such that the leading edge thereof is laterally displaced toward the second segment from the leading edge of the first build ply; applying successive build plies to build on the second build ply, the successive build plies including a medial section of build plies and a last build ply, such that the last build ply partially co-extends with the second segment, each of the successive build plies having a leading edge and defining a thickness, and being applied to a previous build ply such that the leading edge thereof is coincident with, or is laterally displaced toward the second segment from, the leading edge of the previous build ply, the lateral displacement between leading edges of the successive build ply and the previous build ply, in relation to the thickness of the successive build ply, defining a ply drop ratio, the ply drop ratio decreasing up to the medial section and increasing from the medial section to the last build ply such that a surface defined by the last build ply, the first build ply, and the leading edges of the build plies therebetween define a substantially curvature-continuous surface profile extending between the first segment and the second segment; and prior to applying the successive build plies, determining a shape of the substantially curvature-continuous surface profile based on an adjusted ply drop ratio for at least a portion of the successive build plies, wherein the adjusted ply drop ratio is directly proportional to a linear ply drop ratio, and inversely proportional to a softness factor and a ply drop number, the softness factor ranging from 0 to 1, the ply drop number being the number of the build ply between the first build ply and the last build ply.