Dauntless

OMNICELL = equip-able item that has a special ability.
They need components found from defeating Behemoths.
This achievement is fairly simple to get, though it is a little bit of a grind.

To unlock onmicell crafting you will need to progress along the slayers path and "purchase" the
VI DREAD CELL node and then THE MIDDLEMAN character node to the top left looks like a paintball outfit or a space helmet , after this has been done, "purchase" the VII ELEMENTAL MASTERY node and the one to the right called OMNICELL CRAFTING it has 6 coloured squares on a grey background and 5 nodes coming from it
upon unlocking this node it will give you the ability to craft ICEBORNE OMNICELL.
Depending on how well you have been doing you can choose to unlock other onmicell in this category.
Once this node is unlocked you will get a mission from the middleman that asks you to craft an omnicell.

Once you have chosen the omnicell you want to work towards you will need to collect parts from specific behemoths and a fee of the in-game currency called rams. i recommend going with the ICEBORNE OMNICELL since the behemoths should be fairly easy to deal with unlike some of the late game ones which are required for the other omnicell

When you have collected all the required parts and rams for the recipe.
go back to THE MIDDLEMAN select omnicell crafting from the menu
select the omnicell you wish to craft
click the craft option.
then equip from here.
or you can equip it in the inventory via the player menu screen

The achievement should pop once you have done this.

The game itself pretty much guides you to this when you unlock the omnicell crafting node through a quest but i figured i should add the guide since one was required.

happy hunting those behemoths
play nice, keep being awesome.