Multi tool sector

Just out of interest, would there be any way to make a tool changer for a
mill using an automatic draw bar and a solenoid? Could you tell the mill
that to change tools it must move to a certain point, release the draw bar,
move to another, then re-engage it? Or am I going totally off track? I know
automatic draw bars are in the $600 region, how much is it to have a proper
multi tool changer on a mill?

Thanks,
John H.