Why are some things so difficult - to take apart?

[Tony Griffiths]

Thanks to Mike Costigan for sending this gem:

An engineer sat at his drafting board
A wealth of knowledge in his head was stored
Like "What can be done on a radial drill
Or a turret lathe or a vertical mill?"

But above all things a knack he had
Of driving gentle technicians mad.
So he mused, as he thoughtfully scratched his bean
"Just how can I make this thing hard to peen?"

If I make this body perfectly straight
The job ought to come out first-rate
But that would be so easy to grind and paint
That it would never make a welder faint

So I'll put a compound taper there
And a couple of angles to make them swear.
Although brass would work for this little gear
But it's too damn easy to work I fear
 
So just to make the machinist squeal
I'll make him mill it from tungsten steel
And I'll put these holes that hold the cap
Down underneath where they can't be tapped

Now if they can make this it'll just be luck
Cause it can't be held by dog or chuck
And it can't be planed and can't be ground
So I feel my design is unusually sound
 
"Success!" he shouted "Success at last!
This goddam' thing can't even be cast".