The large size worked good for my Dutch Oven, but it was still hard to chew when done.

I've made a couple dry bags out of dog food sacks. They make some of them with a fiber reinforced plastic that's strong, durable, and waterproof. I just sew some 1" nylon webbing with a side release buckle on the open end of the bag and fold it closed like a standard dry bag, and I resew the closed end (inside out) with nylon upholstery thread.

And, as I've mentioned before, I replaced the sack on my backpack with feed sacks made of the same stuff.

I think I'm going to play with the heat bonding technique shown in the video to see how it works on visqueen and those feed sacks. I'll probably go get an old iron at a thrift shop. I've seen little travel irons that might work pretty good for that since they have a smaller footprint.