The engineer has a large arsenal of weaponry: shotguns, springrazors, landmines, and to top it off - a slightly unstable exploding jetpack.
Frag Grenade - Throw the grenade, wait for a moment then... BOOM!
Jetpack - Propel yourself straight up into the air and land with a damaging rocket-fueled explosion.
Spring Razor - A close ranged trap, which lacerates all nearby enemies a few milliseconds after being placed.
Level 5 Unlock:
Shotguns - Ever wanted a cheap shotgun? Well now you can make one! (recipe below)
Level 10 Unlock:
Landmine - Place an almost invisible temporary trap, lasting approximately 2 minutes, which will deal a large burst of damage when stepped on.
Level 15 Unlock:
Faraday Cage - Harness lightning to do your will, as you seal off an area with a swarm of lightning strikes.
The engineer can craft two weapons, the handgun and the shotgun. The handgun is immediately craftable and the shotgun unlocks at Lvl5.