A disc of copper made by continuous casting, the process whereby molten metal is solidified into a "semifinished" state for subsequent rolling in the finishing mills. Continuous casting replaced the creation of ingots using stationary moulds. The process allows lower-cost production of metal sections with better quality, due to the inherently lower costs of continuous, standardised production of a product, as well as providing increased control over the process through automation. After casting, this disc was then etched to achieve its final state.Photo: Alchemist-hp