|this putt is definitely "with the grain"...|
Check out this awesome site showing how an ordinary can of Pringles can be transformed into a versatile putting practice hole. The video on this site is super fun and very creative. I can see these ideas being implemented in Urban Golf.
I also discovered this long-forgotten contraption called "Bobby's Portable Golf Hole" from the 1930's. I have never seen one in person, but I can assume by looking at it that the suspended perimeter rods swing only inward, effectively trapping the ball. The entire top dome can be raised to release the trapped balls. Pretty ingenious. I have only been able to find true vintage holes like this. No one seems to be making new ones, so unfortunately you need $100 or more to get one. A fairly savvy hobbyist could make one, but it will take substantially more work than the Pringles design.
|Bobby's Portable Golf Holes, c. 1930|