I have an old car that has been sitting in my yard for some time and gets decorated with lights for my Christmas show. It is near the porch where candy will be handed out. For my halloween display I would like to rig up a switch (either computerized or a manual pushbutton) that would make the headlights turn on and the horn honk. Headlights are not a problem, my father replaced them with regular lightbulbs I can run from my Ren24 or 595 controller. As for the horn, I have no idea how to rig that up. I have 2 Ren24s and an 80 channel Olsen 595 setup. I want something that can be triggered from outside of the car as I'll be roaming around the yard with a wireless mic and voice changer.
I can usually follow schematics but know nothing about making new circuitry. If anyone could help out please let me know.
Bonus points if I can control it with the computer and also have a manual pushbutton override.
Any help is greatly appreciated