I was asked for an opinion on building a small artificial green- 22' x 7'- for use primarily by one person to hone a sound, repetitive putting stroke. He thinks it should be completely flat, but doesn't know what the better configuration might be: 1) one holes at each end; 2) three holes with one in the middle; 3) one hole near opposite corners at each end; 4) other variations. My advice was to put some minor slope, at least on one side with holes at opposite ends, but he doesn't think the area is large enough to accommodate it.
He didn't ask about the type of surface (I think he has talked to a contractor in the business), but he would welcome input from experienced sources (and clearly I am not one of them). Thoughts?