Your best bet would be to buy a used cheap ultrasonic thickness wall gauge on ebay or Amazon.com You can also look at ones ranging from 1000-2000 dollars at http://www.instrumart.com/ProductList.aspx?CategoryID=5754&Landing=1&s_kwcid=TC|23075|ultrasonic%20thickness%20gaugeS|e|7537765444&gclid=CM_ZmLrwyKoCFcPBKgoddi8w2A
A paint thickness gauge will allow you to find out the thickness of the paint you are using. This means that when this is necessary for particular tasks that you have a good tool to help you.
Yes
No, ultrasonic waves will have difficulty passing through a 1cm thick iron plate due to the high density and thickness of the material. Iron is known to be a good reflector and attenuator of ultrasonic waves, making it an obstruction to their passage.
Year, Make and model need to be taken into consideration, 18 gauge is about the midpoint, some manufacturers / years may be thicker or thinner. The best way to match material size, is to use a metal thickness gauge on a known, good sample.
it can find a sniper from a mile away so it is good for the us army
A great place for almost any used items including ultrasonic cleaners is ebay. There you can bid for items and often find very good deals on items you'd expect to pay more for.
no
It really depends on what gauge (Thickness) of wire were talking about, but plastic and rubber are the most common ones.
Find a good gunsmith.
No, ultrasonic wave do not travel at all in a vacuum.
Kidney Stones
8 gauge minimum, 6 is a good overkill and probably easier to find in the big orange box 10 gauge is sufficient at 50 feet. 10/3 SO cord should be easy to find.