When I worked in a machine shop that repaired machines, they would use a metal putty that hardened when dry that was called phonetically "mougleese" it was from Germany, depending on the mating surface they would fill in chips, worn surfaces, etc, not cracks or breaks that would be repaired with welding. Once it was dry they would re surface it using regular metal working tools. There may be something similar on the commercial market you can fill in the chip, and resurface is carefully with a rat tail file and wet dry sand papers. A race doesn't support the loads like the cup, it might work.