Many moons ago, I worked for an alarm company which specialized in
*extremely* concealed wiring for home systems.We had a new install job where the customer left us the key to his house, then went away on a trip. We spent a week installing his system while he was away. Then left the system un-armed as he did not know his code, how to use it, etc.
When the customer returned from his trip, he called the office and was quite pissed off. He said "Why didn't you install my alarm when you said you would? I just came home and not a thing has been done."
We assured him we *did* install his system and spent a week doing it. He called us a bunch of liars! So we went out and placed the system in audible test mode, then had him open various doors and windows. The buzzer would stop each time he opened a door or window. He was amazed! He then wanted us to show him where the contacts and wiring were and how we did it.
When we installed the contacts in the windows, there was dust and dead bugs at the bottom of the windows. We cleaned this stuff away, installed the contacts and wiring, then added glue over that, then sprinkled dust back over the whole works along with a few dead bugs every here and there. So you could not tell there were any contacts or wiring. Looked like the window had not been touched in years!