Roll top closure, Roll bottom closure

Would probably be heavier than a zipper. What about a UL panel loader?

I haven't compared the clips and extra fabric needed to do a roll bottom versus a zipper. I was also thinking about a zipper to make something like a panel loader.

Does anyone have numbers on comparing weight of a zipper versus a roll top? Thanks.

A roll would almost certainly be heavier than just a zipper. A roll requires not only a certain amount of extra pack fabric, but also a stiffener and closure hardware. But a roll is stronger, more durable, and more water resistant than a zipper, and it affords you some pack volume flexibility. I can think of ways to make a pack with a roll top and roll bottom that opens up into a rectangular sheet (a groundsheet?).

Now that is a possibility. Make it dual use to compensate for the weight.