Search results for Heavy Duty Protective Casing are below:

https://www.skbcases.com/

SKB Corporation manufactured its first guitar case in a small Anaheim, California garage. Today, SKB is recognized globally as an industry leader in the design and manufacture of molded polymer transport cases. Vacuum, rotational or injection molded, these cases are engineered to provide protection for equipment utilized by hundreds of companies involved in diverse industries from music and pro-audio products to military, industrial and medical applications. SKB even supplies maximum travel protection for consumer sports and electronics equipment. -SKB

◊ Note-> Their iSeries cases are manufactured in the USA.

http://www.pelican.com/

Pelican Products, Inc. continues to reign as the global leader in the design and manufacture of high performance Protective cases, temperature controlled packaging solutions, advanced portable lighting systems and rugged gear for professionals and outdoor enthusiasts alike. Their products are depended on by professionals in the most demanding markets including fire / safety, law enforcement, life sciences, defense / military, aerospace, entertainment, industrial and consumer. -Pelican

◊ Note-> Not all of their products are made in the USA - but some of their products (like their line of 'Protector' Cases) are manufactured in the USA.