(from Wikipedia's entry on Hip flasks)

Since the invention of the hip flask in the 18th century, pewter has been perhaps the most popular material choice for liquid storage. It is known for excellent conducting of temperatures and does not change the flavor of the contents over time. It is also great for engraving, making it an easily customizable gift. In more recent years many manufacturers have tended towards stainless steel as a cheaper alternative, but there are still legions of people dedicated to the art of pewter casting and its use for flasks. For more than you ever wanted to know about pewter, check out The Worshipful Company of Pewterers and The Pewter Society.

Blackbird pewter flasks are made in Sheffield, England.

Blackbird - 4oz Hip Flask with Bayonet Top

Blackbird - 1oz Hip Flask

Blackbird - SF222 1oz Hip Flask

Blackbird - Tall 1oz Hip Flask