Thanks, Canon digital. (I'm a photographer part-time)
A few tips --
If ya know a construction worker friend, ask for untreated scraps. My dad and I do custom home building so I'm privy to all manner of wood,scrap,stone,metallics.
I'd use 'hog fencing' for the potato cages. Small narrow rectangular spacing. I've used chicken wire and it wasn't as sturdy and blew around during heavy storms.
Yeah so, try your
local craigslist.org and see if someone is giving away untreated lumber. Some have a good bulk that they're willing to part with.
I'd also suggest checking your local lumber
yard. A myriad of various woods and scraps to
boot from the mill. A way to save it from fire, or landfill.
Most of all just have fun with it, and exercise your creativity... That tends to make people smile.
An alternative? I've collected flagstone from jobsites. Here's a onion/radish companion bed.
I've even done cedar shingles on a bed. Vine tomatoes. Check it out.