Guns, explosives have chemicals, moving parts.
4 seconds sound clip from the Terminator 2: Judgment Day movie soundboard.
You can hear this line at 00:44:37 in the Blu-ray version of the movie.
Quote context
[...]
- Like, it could disguise itself as a pack of cigarettes?
- No, only an object of equal size.
- Why not just become a bomb or something to get me?
- It can't form complex machines.
- Guns, explosives have chemicals, moving parts.
- But it can form solid metal shapes.
- Knives and stabbing weapons.
[...]