Great ideas.
I really do keep my everyday tools in a clear plastic cosmetic case. This goes with me wherever I take my machine. I have another clear plastic bag [a gift] with the usual thread colors: greys, black, white, cream, and tans and my bobbin ring with extra bobbins. I add to this as needed.
My cushion is next to my machine so I won't forget to take it. My cutting mat is next to that as is my serge protector extention cord.
My sewing machine manual is with the machine when traveling.
I never take an iron unless specifically told to as they do use a lot of power and where I go to quilt or take classes they already have the irons.
This is Arizona so whenever I leave the house I have my topped coffee mug that I use for water only with me.
Gads, but I do have plenty of totes to put it all in the nite before any class with my checklist. Since I have a garage I can prepack the car the nite before if it isn't too hot. Then I will place my things near the kitchen door out of my way for packing the next day.
Can you tell I am a list maker?
ali