Complex sentence: Once the designs were approved, the artists prepared bronze casts to be sent to the Medallic Art Company in New York, where hubs would be made that the Mint could use to produce coinage dies, as they could do it faster than could the Mint.
Split into simpler sentences: Once the designs were approved, the artists prepared bronze casts to be sent to the Medallic Art Company in New York. There hubs would be made that the Mint could use to produce coinage dies, as they could do it faster than could the Mint.