Wine barrels are an important part of the wine making process. The history of cooperage and wine are interlinked. Making a watertight boat probably led to the making of a barrel.
Around 350 B.C. the Celts elaborated rounded watertight recipients that were able to withstand stress (from rolling) and weight (from stacking). Ever since that time the barrel has been manufactured using basically the same .
Check out this youtube of barrel making completely with hand tools. The work out actually happened at work instead of at the gym.