1. A method for constructing an integrated circuit to implement a plurality of custom logic functionalities, comprising the steps of: comparing the netlists for said plurality of custom logic functionalities; and identifying which connections within said netlists (hereinafter “netlist connections”) are common to all of said of custom logic functionalities and which netlist connections are common to some but not all of said of custom logic functionalities; and creating an integrated circuit layout including logic cells, field programmable switches, and hardwired metal connections, where the netlist connections common to all of said plurality of custom logic functionalities are implemented with hard-wired metal connections and the netlist connections common to some but not all of said plurality of custom logic functionalities are implemented by a combination of hard-wired metal connections and field-programmable switches.