The other day when I was putting my flute together I thought about how my hands just seem to know where to go, putting the headjoint onto the main part of the body of the flute.  I'm familiar with how the embouchure plate feels in the palm of my hand so that usually when I put the headjoint on, it's almost in the perfect spot.  There might be a slight adjustment that I do when I hold the opposite end of the flute – the foot joint – and look down the barrel to see if the tops of the keys line up with the opening that I blow across on the headjoint.  Most of the time there's just a slight adjustment to make.  And I thought about the fact that I've done this assembling of my flute hundreds, probably thousands of times.  Even with the periods when I haven't played my flute – it's still something that is so second nature to do.   
Instruments really do become like an extension of your own body.  Instruments are not just pieces of metal or wood with strings and stuff put together by craftsmen, it's more like a living thing in a way.   Each musician knows the feelings of the keys – or strings – under their fingertips, it's a very individual, personal thing.  I like that, and I think that's something that comes across when a musician plays.