Thermal packing cube
I love my Tom Bihn bags, but I'd like to see an insulated packing cube in the Aeronaut half cube size (so I could have one with cold food and one with hot food) or full size. California Cooler Bags (Manufacturer of cooler bags, cooler totes, insulated bags and much more) makes some really nice cooler bags, but none of them are the right size for slipping in my Brain Bag.
Have you looked at the Kelty Toto? It's a fantastic little cooler, lunch sized. It is durable and holds more than you'd think. We have used it for travel, picnics...