Waaaay Cool. This was one of my most emotional reasons for buying a riding mower in the first place.
I've gone to Sears several times with the intent of buying a roller (one that you fill with water) in order to do this exact thing. It seems that you've done the same thing and saved a tone but:
1) Is it sturdy enough that it will make the grass really lay down? Those rollers hold a great deal of water (weight) to do their job.
2) One of the reasons that I hadn't bought the roller is that the biggest that I could find is 36". My deck is 54". I couldn't visualize what my lawn would look like the a 36" stripe going onw way, 18" on each side not rolled and sticking straight up (9" from the forward pass, 9" from the reverse pass), then 36" rolled the other way.
This may be was overcomplicating things but in my mind I imagined a kinda MoHawk looking effect.
3) Could you detail the materials and thr construction of it? It looks like simple mudflaps from say Tractor Supply Co kinda tied together, and maybe some weight on the end?
Again Great Job. I love to see great ole American Innovation in action!!!