Design me a Product

I'm looking for a PCB circuit design with below given specification: 1. Input source is 12v. Provided by using a 220v AC to 12v DC external converter circuit (input can be taken as direct source without displaying converter module in circuit but voltage spikes possible in 220v raw input source) 2. Perform 12v to 3.3v precise conversion to power ESP8266 with circuit protection. ESP should be protected from any known threats (may be optoisolated or other component based protection to be used). 3. Output of ESP as a 3.3v control signal is used in 12v based relay to power an output which goes to a 12v device with 3 Amp, 12W consumption, 4 Ohm electrical resistence. This output device will not be a part of this circuit design. Protection may be provided to the microcontroller with optoisolated or freewheeling diode or any other appropriate means possible. 4. Heat consideration shall be taken as the circuit would be powered on 24x7x365, thus components should not be operating at their maximum limits. Temperature protection, over-current protection and short circuit protection shall be done where required. 5. Other considerations: Circuit isolation, Voltage spike protection Will need a very short explanation of components used, Gerber and other source files so that future changes can be done. Do let me know the software you'll be using for designing & simulation and the type of circuit protection that you'll use. The components & design should be such that its high quality with lowest possible cost.