cages

I read about using cages in the book. I'm considering this because I know there are rabbits and squirrels on the property. Construction instructions indicate 4 ft sides so i'm assuming this sits on top of the the 4x4 ft box. Seems to me it would be better for it to be larger than the box so it sits on the ground.
Does anyone have experience with using the cages? What works?

Cages that sit on the ground interfer with mowing and weed-eating around boxes. Cages that sit on the wood bed can crush bushy or drapy plants.

I pondered this , and went with a pvc and bird-net with pvc legs fitting into metal u-shaped clamps. One benefit is simple to build. A handsaw to cut pvc and a screwdriver to attach the clamps to the box -- inside the box.

Zip-ties tighten the mesh enough to tug down over the sides of the bed so critters can't climb on up. Also netting keeps birds -- danged blasted crows -- from eating my seedlings.

It's tough to find the perfect durable critter cage. I have the kind described in the book that's made with wood and chicken wire on most of my 8 boxes. For an immediate solution it worked rather well the first couple years. But they age faster than I expected. The oldest cages are 3 years old and the plastic zip ties are snapping off and the wood has become wobbly and warped. When I put on shade cloth it catches and tears from sharp wire edges. I could cover those edges with duct tape but don't like that idea. Plants around the outside edge get shredded or torn up somewhat too. Getting tired of that.
I've looked for years at all the pictures on this forum and my replacement covers will be pvc with soft netting. Will those last longer than 3 years? We'll see.

PVC pipe has a short lifespan in direct sun. That's OK. IF I like this cage into the fall -- so far it's PERFECT -- I'll rebuild it with electrical conduit and velcro, or maybe pipe strapping. But it was an experiment to see if:
1) I could keep from smashing plants on the edge -- YES
2) It would stay up off the ground for mowing -- YES
3) Keep nasty crows and rabbits off my LUNCH -- YES

It started life on the potato bed, then moved to the 4-sisters bed, and is currently sitting on a daylily bed because I haven't finished filling the second 4-sisters bed yet... then it will move there for a while.

Thank you. Then I'll scrap pvc since my beds receive over 12 hours direct sunlight. Looks like conduit is the next choice. I have roof shingles that ring all the boxes effectively eliminating weeds. New cages could sit outside the box but will need to be taller to compensate for the height of the wood bed. Have to keep it very simple, probably building it myself.