Thanks Shawn. This is becoming an excellent list. I will only add a few things I don’t think have been mentioned.
People seeing that large 7x17 have actually asked where they might see or buy my work? Who am I to question their wisdom? I carry a small pack of business cards.
A professional carpenter friend told me that the smaller the bubble level the less accurate. The extreme being the tiny little things on our cameras or tripods. I carry a nine inch level with horizontal, vertical and 45 degree angle bubbles. This fits nicely front to back or side to side on either 8x10 or 7x17. It says Johnson Level & Tool on it, but there are many brands. They are available anywhere tools are sold.
I still carry a 2” face analog Heuer stop watch for those long exposures at f 45 and f 64. Yes I carry a smart phone that has a better one, but I am shooting analog and I like old watches.
There is a quart zip lock with: small pocket knife, 3’ Stanley metal tape, tweezers, slot and Phillips screw drivers, needle nose pliers, Linos or Rodenstock flat stainless Copal shutter wrench.
Long ago I read that a flat, 1/8” thick perforated 5.5” rubber pad, normally used in the kitchen to open jar lids, will keep a large camera from twisting on the tripod head. They wear out easily so there are two in my bag. I have found these in hardware or kitchen supply stores.
In the car I carry a two part five minute epoxy plunge dispenser and sand paper.
A thermos of hot coffee. Boy is that nice a couple of hours into a shoot, especially on a cold day.
The area where I am shooting is bordered by Lake Erie. A very commercial Cuyahoga River winds through the Flats. 600 foot freighters move up and down the river, by themselves, or with one or more tug boats or barges. The curves in the river are so sharp that the ships have to almost stop in the middle of the turn. Even high f stops and long exposures work there. Problem: When is the ship going to come up the river? When are the bridges going to swing or go up? Will there be a tug or two? Does a ship have to wait for a train to cross the lift bridge?
All commercial vessels have transponders just like airplanes. Marinetraffic.com has a cell phone app that will tell you what ships are in Cleveland, what ships are approaching or expected in Cleveland, at what time. At one minute intervals a ship will show as a moving dot on a map that also shows intersecting streets. This app reports on any marine traffic, anywhere in the world.
I’ll consult with the yellow Labrador ladies and see what else comes to mind.