a standard hardhat that has been laboriously hand tooled with heavy equipment, including a bulldozer, road grader, dump truck, and crane. Made in Indonesia for Americna oil rig workers

originally it was a McDonald Mine Safety Appliance Co. hardhat

http://www.dinosaursandrobots.com/2009/03/amazing-hand-tooled-aluminum-hard-hat.html

This collection was on display at the Ricco/Maresca booth at The Metro Show. Individually, the hand-tooled hard hats are personalized with names and adorned with motifs custom-made by craftsmen in Indonesia for Americans working on oil rigs on the island nation.

http://www.artsobserver.com/2012/01/21/ricco-maresca-gallery-displays-26-vintage-hard-hats/img_0408/