A stack of layers for use in making a composite, the stack comprising: a core including a stack of one or more non-woven layers, one of which defines at least a portion of an upper surface of the core, and one of which defines at least a portion of a lower surface of the core, at least one of the non-woven layer(s) having: a first set of resin fibers, each comprising at least a majority, by weight, of a first core thermoplastic material having a first core transition temperature and a first low-shear viscosity; and a second set of resin fibers coupled to the first set of resin fibers, each of the second set of resin fibers comprising at least a majority, by weight, of a second core thermoplastic material having a second core transition temperature and a second low-shear viscosity; wherein the first core transition temperature is at least 10% lower than the second core transition temperature and/or the first low-shear viscosity is at least 50% lower than the second low-shear viscosity; a first set of reinforcing fibers coupled to the first and second sets of resin fibers, each of the first set of reinforcing fibers having a modulus of elasticity that is greater than 8.5 gigapascals (GPa); and one or more skins, each including a stack of one or more layers, each having unidirectional or woven fibers dispersed within a skin thermoplastic material; wherein each of the skin(s) is coupled to the core such that the skin covers at least a portion of the upper surface or the lower surface of the core. a core including a stack of one or more non-woven layers, one of which defines at least a portion of an upper surface of the core, and one of which defines at least a portion of a lower surface of the core, at least one of the non-woven layer(s) having: a first set of resin fibers, each comprising at least a majority, by weight, of a first core thermoplastic material having a first core transition temperature and a first low-shear viscosity; and a second set of resin fibers coupled to the first set of resin fibers, each of the second set of resin fibers comprising at least a majority, by weight, of a second core thermoplastic material having a second core transition temperature and a second low-shear viscosity; wherein the first core transition temperature is at least 10% lower than the second core transition temperature and/or the first low-shear viscosity is at least 50% lower than the second low-shear viscosity; a first set of reinforcing fibers coupled to the first and second sets of resin fibers, each of the first set of reinforcing fibers having a modulus of elasticity that is greater than 8.5 gigapascals (GPa); and a first set of resin fibers, each comprising at least a majority, by weight, of a first core thermoplastic material having a first core transition temperature and a first low-shear viscosity; and a second set of resin fibers coupled to the first set of resin fibers, each of the second set of resin fibers comprising at least a majority, by weight, of a second core thermoplastic material having a second core transition temperature and a second low-shear viscosity; wherein the first core transition temperature is at least 10% lower than the second core transition temperature and/or the first low-shear viscosity is at least 50% lower than the second low-shear viscosity; a first set of reinforcing fibers coupled to the first and second sets of resin fibers, each of the first set of reinforcing fibers having a modulus of elasticity that is greater than 8.5 gigapascals (GPa); and one or more skins, each including a stack of one or more layers, each having unidirectional or woven fibers dispersed within a skin thermoplastic material; wherein each of the skin(s) is coupled to the core such that the skin covers at least a portion of the upper surface or the lower surface of the core.