A method for making a customized sole insert for a user is disclosed. The insert is first manufactured in various sizes, widths and arch heights so that a user may select the insert best configured for his foot. The insert is initially comprised of a bottom layer or shell; a formable layer which can be hardened into a particular shape; and a top cushion layer for contact with a wearer's foot or sock. The shell has an aperture for injecting a hardening agent to accelerate the hardening of the formable layer. After the insert is selected, the hardening agent is injected through the aperture and the wearer stands upon the top cushion layer until the formable layer has hardened. The result is a formable layer which is substantially conformed to the plantar aspect of the wearer's foot.