I would suggest you route out the size hole you require or place cup on spool where you want holder to be and draw a circle large enough to take the cup or cups.
Drill down as far as necessary lots of holes around the circle. Then chisel out the timber until it will take the cup. Then sand it until smooth and finish with oil or paint or whatever is required.
Or Do you mean fit cup screws to take the cups?
Can you show us a picture?
What kind of spools, and what size are they?
Individual cup holders?
Can you be more specific about your project? A picture and plans? Where are you planning to put this?