You are better off to take too much then not enough. You can always leave it in the car, and bring it in if you need it. Don't stress over it too much, as far as supplies. Go through each project and make sure you have tools and material. If you forget, someone will loan you their tools. There is always one person that shows up to a retreat with her sewing machine in a rolling cart and one carry tote with her projects in the other hand. I call her the "One trip wonder". Not me, I always have to make several trips to the car to get set up. Just enjoy, and don't worry about how much you are bringing.