The kids decorated this bag together the other day for a friend’s birthday. It’s a shopping tote that zips into pouch-shape so you can store it in your purse and have it handy. Here in Germany pretty much everybody has re-useable totes because you have to pay extra for grocery bags.
The bag comes from dharma trading, which has a ton of other bag options for very reasonable prices. I think you can get some blank totes at Michael’s, too, but maybe not the lightweight zipper kind like this. The kids used Sharpies because we couldn’t find our Tee Juice markers, but I would recommend the fabric markers because the colors will wear better.