As an engineer "main" in FF, I have to throw this stuff in:
1. Multi-Turrets
http://firefall-wiki.com/w/Multi_Turret
Higher Tiers or certain customization aspects could change: Damage, Duration, Max. Turret count etc.
2. Refill-Stations
Ammo refill basically. Could be on a resource (X amount of clips refilled) or time counter before it runs out
3. Deployable Shields
Provide cover for allies, lock down chokepoints.
Could let "Friendly" shots and Frames through but keeps out the creeps.
4. Actual moving 'n' shooting Drones
Think those Lil' fellas from the FF Cinematic.
They could provide firepower depending on which weapon type was used to craft it.
Maybe buff Companions accuracy with sensor Drones or boost their shield regen.
They also could repair Omniframes on the go and during combat.
May have a Fuel/Energy timer.
5. Repair Beam/Station
Since the Omniframe WILL need armor repair and the next base could be far away OR during an invasion where you can't go back to base and may need fast emergency repairs
6. Health/Ammo/Repair-Kits
Basic Consumables like this would be good for those who go somewhere solo, like while scouting (if that's gonna be a thing).
7. Decoys
http://firefall-wiki.com/w/Advanced_Decoy
http://firefall-wiki.com/w/Decoy
Be it holographic or physical. Decoys could be used to trick enemies into an ambush or divert their attention to somewhere else while the real you blows them up.
8. Flamethrowers
Because mowing down hordes of enemies in a cone in front of you with fire looks badass. Also, Alien BBQ.
Could count as energy damage stats-wise.
Maybe modify projectile type to balls of fire (Basically fire-grenades).
Looking at you with these two
@Torgue_Joey
9. Grenade-Launchers
Blow shit up from afar.
Would deal Explosive/Splash Damage...
Could be modified for energy/plasma grenades or Something along those lines.
10. Shoulder Mounted Mortar and Missile Launchpods
For blowing shit up from REALLY far away.
Don't use up close though, you might damage yourself or others with it.
Might want to use a Medium to Heavy-Type Frame for those
I may add more to this once I got more ideas.