The BOLT particle will freeze any particles in a 3x3 area upon it colliding with something, It can release if pushed or broken.
Extra: SLCR, Slicer, Will remove a line of material upon collision untill the cut hits air, the line will travel in it's direction of movement and will also slice anything that falls on it untill air is reached.
EXTR: Extruder, will use it's Ctype to extrude any solid material so it's basically a clone that works in one direction and can push stuff. and different ctypes of the same extruder would result in some cool things like electronics production.
Bullet has been suggested and I think they where testing it.
NUCLEAR_FOX:
Bullet has been suggested and I think they where testing it.
there is no stating of an "bullet"
The BOLT particle sadly isn't exactly possible. Not without a fair bit of hacking in the SRC.
The upcoming STASIS wall fulfills a similar enough purpose.