Selecting and cutting the oak staves.
Drying the staves: Either outdoors or in a kiln; greater quality results with the slower, steadier outdoor method.
Sizing and shaping the staves.
Assembling the barrels.
Toasting the barrels. This process caramelizes the inside of the barrel, ameliorating the tannin flavors that the wine will extract from them. Different degrees of toasting result in different characteristics and flavor profiles.
Fitting the barrels with caps and hammering the metal support rings into place.
Quality control: sanding, testing for leaks, and punching the bunghole. At this point the barrels may be branded with a company seal and sent off to the client.