Ok, I have gotten upto this one and now I am stumped.
"Two with a stone, a ball in a box"
I was thinking the pebble shotgun, but it doesn't work. So atoms being a ball, I was thinking the fuel cells, becuase they are radioactive isotopes (or something like that), but that doesn't work either. I also thought that the security box might be it, I have the keycard, but I can't find the box (where is that damned box??). But that's probably not it either. Any help appreciated.