I made a couple of picnic tables recently.
The first is a rounded top for my neighbour, to fit a standard table which had the top glass missing. It is made of pressure treated 5/4 boards.
The second one was requested by my in-laws. They sent me a Youtube video with instructions for an octagon table. (It was nice using someone else’s design for a change!) If you are interested, here is the link to the first video (there are four): https://www.youtube.com/watch?v=DSliTVOxKlc
If you are in the area and would like one, I can make another one out of pressure treated lumber and deliver it for $700 including tax. You need a flat/level square of ground, 6.5 feet x 6.5 feet minimum.