Homebrew PCBs

I think it would be useful to make a wire bonder for 'dead bugging'
BGA's sometimes, or for other small device work. Especially for quick
proto development or rework.

Anybody have ideas on this. I was thinking ultrasonics or mechanical
vibration. It would be nice to do copper wire bonding if possible,
though silver or gold would be useful( but more expensive ).
-Lee