Z

 is an item used to craft the Synthesizer v3.

Obtaining
Z can be obtained by using an Atominizer on a Zee. A Zee is spawned when 2 Wais come into contact, which can happen after they are lead to each other with the Charminizer.

Synthesizer v3
Up to 60 Z can be placed in the Synthesizer v3 to gain per item.

Essence Crafting
Z can be used to add Stars to Shimmering Light Armor.