Reddit reviews Marble Drilling Bit

It depends if you want to use a drill press this may work better,

Marble Drilling Bit https://www.amazon.com/dp/B002L6M1U8/ref=cm_sw_r_cp_api_15gTAbVHAZWGP

you probably should not use a router bit it your drill press. If you have a router you could pair the router bit with a guide bushing on your router ( make sure the sizes of the bushing and not are compatible)

http://www.rockler.com/guide-bushings-guide-bushings

And the you could make a template for the layout of cups you want.

Hope this helps

Edit: spelling