Combat Wrench item is Item_4818, and the projectile is Projectile_902. I also found an identical sprite (Projectile_925) and I'm not sure what that one is for, maybe the mechanic herself? Though I would expect that to have a lower number if it was different...
For the ballista tier 1 is Projectile_677, tier 2 is Projectile_678, tier 3 is Projectile_679, and the bolt itself is Projectile_680.
The summoning items are Item_3824 for the rod (tier 1), Item_3825 for the cane (tier 2), and Item_3826 for the staff (tier 3)