If I want to waterproof a PCB can I just stick it in a mould and fill with resin? If so - which resin? Polyester or Epoxy? If not - what? Do I have to do anything special with the wires or just make sure that the end of the insulation is inside the resin? Can I do the same with the back end of a switch? (There is a rubber oover on the fron, toggle, end)