I’ve just got back from a short trip to Dartmoor (there’s a bit of a story to tell there) and one of the new bits of gear was a Tread Lite Gear Packing Cell. Mine was one of a limited batch in cuben but Paul is now making them available in silnylon. The silnylon ones are actually slightly lighter 26g vs 30g, but the same size 32x16x16cm.
It fits nicely into my Lightwave Ultrahike and I’m sure it would fit into my other packs. I think it’s a neat idea. If you’d like to see more, pop over to Paul’s eBay store.
Disclaimer: this product was purchased with my own money and I have no financial relationship with Tread Lite Gear.