I haven't taken a picture of mine in a while, but here is what it looked like once upon a time.
It's a bag that I bought from Yankee Candle at Christmas -- $5 with $35 purchase or something like that. I thought it would be perfect for my yarn projects!
Inside is has a pattern pamphlet, a Knitting Guide, and a small cosmetic bag with some odds and ends in it, like a tape measure, some crochet hooks and stitch holders. Common items that I don't use often and so can get by with only one.
It also holds two small project pouches. In this picture, they are stacked on top of each other to make room for the skeins, but I normally do not carry so much yarn around with me. (That was the point of this particular picture -- to show how crammed my bag was.)
Each project pouch has a pair of scissors in it, as well as the yarn, needles and pattern for whatever I am working on. I work on two projects at once -- one small "complicated" project and one "easy" project for those times that I can't, or don't want to, concentrate on what I am doing.
Often, I leave the bag in the car and just carry a pouch by itself into wherever I am going.
At the moment, my easy project is a log cabin blanket and it has gotten too big for both bags. The pouch still has the pattern and the scissors, but I have had to move the yarn and the work to other containers. I don't think I will be carrying around anymore and am contemplating a new, small, little thinking required project to replace it in my carryall. (Like the KH February or May KALs.

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