I was thinking about setting it up with 24 posts spaced 8ft apart for a circumference of 192ft and a diameter of just over 61ft.
I chose 24 posts because I'd measure out the first 12 like a clock and then space the second 12 halfway between all of the others.
As far as the height goes... I was thinking 4ft solid walls, attaching the boards to the inside of the posts for a smooth interior. Is that tall enough?
Sand is another thing I'm not sure of. Is it strictly necessary or would grass be fine for starters?
Any other tips are welcome too :)