Setup:
1- Place a towel on the practice green about 15 yards away from the fringe.
2- From the towel, take 15 paces in the opposite direction of what you just measured to the fringe. This is your chipping spot.
Drill:
1- Chip a ball past the towel, rolling as close to the far fringe as possible without hitting it
2- Chip your next ball. It must stop short of the first ball but past the towel.
3- Repeat again and again, squeezing as many balls as you can between the towel and the previous shot until you either go short of the towel, or past the previous ball.