Sable

There are four Machinist Badges you can earn in the game:

1. For constructing Simoon during the first segment of the game
2. "A Stubborn Snag" quest, given by Machinist Utarii in Burnt Oak Station
3. "Lightning in a Bottle" quest, given by Machinist Zahra in Seven Sisters Station
4. "An Eye to the Sky" quest, given by Machinist Kaalan in Marrow Bone Station

Once you have three of these badges, take them to the Mask Caster tent in any of the aforementioned stations, and you will receive your Machinist's Mask.