Gear Shards of a specific quality (can be obtained from the Campaign, Events, Crafts, Trade Shop, Idle Rewards, Tower, Grand Event's Orbs & Parts chest and more)

Gear Scheme of a specific emblem (can be obtained from Trade Shop, Grand Event's milestone rewards and more)

As a reward in the Eternal Chests (get keys to those by exchanging Friend Codes, buy for Gems in Trade Shop, buy for Gems in Chest, buy offers.

As a reward in the Event Chests (located in the Grand Event)

As a reward from Keys (you can get keys as a reward from Events, offers, or craft them from the Key tab in Craft)