Everyone's plein air setup is unique. The items I bring outside with me are slightly different from what another artist brings outside with them. I always enjoy seeing what kind of supplies other people have, and thought it might be fun to share mine, so here are some of the most useful supplies I take when I go outside to paint:
First and most important is my easel, which is actually a tripod with an easel attachment. I like using a tripod instead of a more traditional wooden plein air easel because they're lighter, quicker to setup, and I think they handle uneven ground a bit better.
I also use an umbrella (which isn't shown in the picture) to give me some shade while I work.
I use a small cart/bag on wheels to carry my supplies.
In my bag I have:
Small sketchbook, pencils, an eraser, as well as a view catcher.
A paint brush that I use for wet underpaintings and brushing off dry pastel.
Roll of artist tape, and some bungee cords. The tape is good for taping my pastel paper and I sometimes use the bungee cords as a paper towel holder. If something were to break (like the time the leg of my last easel broke) bungee cords and tape are also handy to have around for temporary fixes.
Paper towels are a must, as well as leak-proof containers for water and mediums.
Aluminum foil for making pastel dust catchers.
Watercolor isn't a medium I work in often, but I like to carry a travel watercolor set because it's great for making quick sketches and color studies.
Sunscreen and bug spray.
A snack and some drinking water.
Compostable dog waste bags. These are the best small trash bags! They're great because they come in a holder that clips onto my bag. They're also small, inexpensive, environmentally friendly, and it's easy to get refill rolls for the holder.
That's all my most essential plein air painting items. If you have any questions or plein air supplies that you love and would like to share, comment below.