Learn English – “Very simple!” or “Very simply!”

If you had taken up woodwork as a hobby and made your first object, lets say a wooden jewellery box, and someone asked you:

That looks beautiful. Did you make it?

You would proudly assert:

Yes, I did actually. I made that box with my (very) own hands.

Note, you could (idiomatically) insert very in the phrase without changing the meaning. The fact you place the adjective, own between the possessive adjective, my, and the noun, hands, means you are emphasizing the ownership of the hands that crafted the object. If you had replied:

I made that box with my hands.

Your listener would understand that you were the carpenter or maker of this object but it would sound odd, because you can't make an object with someone else's hands. You would never say: "Yes, I made it with his hands". It sounds not only gruesome (!) but obviously illogical. More typical expressions would be:

• Yes, it's handmade
• Yes, I made it by hand

The above expressions tell your listener that the object is crafted by hand, that very little machinery was involved in the process or if that were not the case, that you handled the machinery or mechanical tools yourself.

A more unusual way to express the same idea would be to say:

• I made it with these very hands

I would place the stress on "very" and probably hold my hands, palm upwards, to show the various cuts, nicks, scars and calluses that might be present as evidence that I am an experienced carpenter.

The Google Ngram seems to be heavily in favour of "by hand" but please do look at the different links below the chart to see how each expression can be used.

EDIT: Very when it is used as an adjective

There is a very famous and beautiful song sung by Nat King Cole entitled

The Very Thought Of You

The first two lines are

The very thought of you and I forget to do
The little ordinary things that everyone ought to do

In these lines, "very" means mere, simple, and plain. Just the simple thought of his loved one is enough to make him forget about the dull and insignificant moments of his daily routine. The meaning is slightly different from that quoted by the OP, "precisely as stated or being exactly the same and not any other"

However, returning to the OP's sentence,

Yeah! Trust me. I saw her with him with my very eyes

in this example very carries another different meaning. The Chambers Dictionary gives the definition for "very" used this way

adj. used for emphasis, [...] precise, actual (this very minute, her very words)

Thus the speaker is emphasizing that he saw the woman with a man, presumably not her real partner, with his actual eyes (in other words he didn't hear the news from anyone else) and therefore, to take his word for it.

"Very" has come to indicate a great degree or extent, but this is not the only, or even original, meaning. Ultimately, "very" comes from the Latin for "truth". If someone is "very tall" then they are "truly tall". Over time it has taken on an emphatic meaning, perhaps by indicating that the phrase is more than mere hyperbole or by suggesting that what is claimed would be true by any standard. You might call a person "tall", who appears short to someone else. Calling someone "very tall" suggests a matter of fact, rather than opinion. The underlying meaning of this usage has been forgotten over time.

In other uses, the implied "truthfulness" can have a restrictive or limiting effect, rather than the emphatic effect you are expecting ("the very house" and not some other). It can be useful where the phrase might be surprising or incredible without it. Consider the phoenix, the very death of which gives it new life.