Among your marks, you will find a paint freak, someone who is always touching up his house, car, fence, kids, et cetera with paint. Simply slip some luminescent paint into his bucket or sprayer. whatever he covers with the conconction will show up eerie as hell at night.
Copper paint is a very effective addition for dressing up electrical circuits. Several readers suggested painting a thin line of copper paint down the insulator of a spark plug, for instance, running from metal to metal. If you do it on only one plug out of four, you can create electrical havoc for a mark’s car by disrupting the normal circuit flow. The best part is that 99 out of 100 mechanics will never spot it as the problem…and all the while their $$$$ service meter is running.