The blueprint for Harvester has a chance of dropping from slain monsters.
Upgrading the Harvester will increase the harvest speed and max capacity.
There's roughly 100 Element-X in every spot and you will most likely run out before you manage to fill up your Harvester. Do not upgrade your Harvester because most of the time the new spot will spawn out of range from your harvester and you will need to build another one.
Harvests 1 Element-X every 10.4 seconds.
Max capacity 600
Harvests 1 Element-X every 9.2 seconds
Max capacity 900
Harvests 1 Element-X every 8.2 seconds
Max capacity 1050
Harvests 1 Element-X every 7.3 seconds
Max capacity 1200
Harvests 1 Element-X every 6.6 seconds
Max capacity 1350
Harvests 1 Element-x every 6 seconds.
Max capacity 1500