just slap some isolated high current relays on your proto board and use a resistor or reg to power them. You would probably want switched current going through the wires on the normally open relay circuit, then have a normally closed "e-stop" switch that cuts power to the relays when it is pressed. Make sure the switch stays open and it is not a momentary switch. Please let me know if this is right or if you understand what I am talking about. All in all it should be $20-$30. I remember seeing e-stop buttons in my mouser catalog (
www.mouser.com)