A case for a set of 6 drill stops (of unknown provenance).  The lid slides on.

The drill bit stops that fit in this case have dimensions (aka drill size, along with stop ODs):

• 1/2 in (20 mm OD)
• 7/16 in (17 mm OD)
• 3/8 in (16 mm OD)
• 5/16 in (14 mm OD)
• 1/4 in (12 mm OD)
• 3/16 in (11 mm OD)

As pictured: Case Body printed in yellow PETG; Case Lid in transparent PETG; 0.4mm nozzle, 0.2mm layers.