First up, here is the large version - designed to carry large loads - the strong handles go all the way under the outer pocket, across the bottom and back up the other side - making it suitable to carry bottles of water, or, as I am reliably informed THREE bottles of wine! Now, that'd be a great picnic!!
There are frames that support the opening of the bag, they add structure, and hold the bag open so you can load it up.
I decided to make mine as a lunch bag, so I used laminated cotton for the outer fabric and used PUL for the lining, so the bag is completely waterproof.
(www.craftsy.com/user/pattern/store/2657567 and www.etsy.com/shop/twoprettypoppets)