I chose a simple frame made from left over wood from another project. On that frame I strung jute twine and then looped a piece of twine around each plant.
At first I was cutting the twine after each plant, but by the end I realized I could just run the twine along the ground between each plant. The next morning I went to check on them and it turns out peas were born to climb. Give them something to climb and the small tendrils will wrap tight and the plant moves upward.
I did find this process somewhat tedious, but it was inexpensive and when our growing season is over all I have to do is cut down the twine and toss everything into the compost. With a trellis I would have had to untangle the plants from the structure. I know this about myself, I am better at front end preparation so this seemed like the way for me to go.
Provide support for your climbing plants. Your peas for one will thank you.