Tool gizmo shells are used in the Invention skill to generate perks for use on augmentable tools.
Researching the ability to create a tool gizmo shell at an Inventor's Workbench requires level 22 Invention. Creation requires 10 Head parts, 5 Crafted parts, and 2 Precise components, and rewards 550 Invention XP and 50 Crafting XP.
Using a tool gizmo shell opens an interface allowing you to combine different materials to generate perks. This creates a tool gizmo, which can then be used on an augmented tool to give it the perks.
Tool gizmo shells were not included in the initial Invention release on 25 January 2016, but were introduced on 14 March 2016 with the "Invention Skilling Update".
