I’ve always had good luck with this company

https://www.kinsmangarden.com/category/Plant-Supports

The problem I found before I gave up on the idea of peony supports it that many of the full doubles were bred to be cut flowers with long stems above the foliage. You have to decide if you want to support the foliage or the flower. If you only support the foliage, at least in this area the flower stems will break when there is the normal heavy rain. Supporting each flower so that the support cups the base is time consuming, looks strange, and is hard to find.

I have too many to afford the gorgeous cages that Kinsman has, so I got the 32" wire folding fence from Amazon/Home Despot: @$18 for 10 panels, and most plants get 3 or 4 panels, while the behemoth Festive Maxima get 5 or 6. You can barely see them when the peonies are fully leafed out. Some of the taller ones, like the FM, flop a little if it rains on the flowers, but it's better than falling on the ground, IMO.

lisanti, I wonder if I already have this folding fence. I ordered a box from Menards to corral tall New England asters. Mine has arched tops - 2 arches per panel - and about a 3-4 inch gap in between the arches that is much lower. I found stems always slipped down in between the arches so I still had to fool around tucking stems back in: or run a wire across the top. I would not buy that particular design again.

Is yours straight across?

I've got the arched and double-arched. There is a gap between the tops of the fence, but the wire that connects one panel to the next stops the stem from hitting the ground, which was the main problem for me. This is one of the ones I got : https://smile.amazon.com/Amagabeli-Decorative-Garden-Rustproof-Ornamental/dp/B06W54K9N2/ref=sr_1_3?dchild=1&keywords=folding+fence&qid=1587564137&sr=8-3. I have to say that the price has about doubled since last year, probably due to the COVID virus for one reason or another. Don't spend this much money on them; maybe Home Despot has them cheaper.

Try using tomato cages.

beesneeds, I do use tomato cages for smaller plants. But even the largest widths I have found won't corral the biggest peonies. I measured the big, thick, heavy ones I have yesterday: the width of the top ring is 16. " I need closer to 24"

lisanti07028 , that's similar in style to what I have. Though I doubt mine are that tall. I remember having to special order them from the store and pick them up. I will check their websites.

Use 2-3 smaller tomato cages?

I bought a square cage at Menards this spring to try out. Coated green wire, they fold, I think it was around $10.

http://www.ezgrowcage.com/products.html

These ones work pretty well, although I wish the 28 inch one were a bit taller. My garden center sold them last year for the first time, hadn't seen them before.

I was planning to spring for a 4 foot one to see how it would work, that one could be too tall and not tapered correctly for peony.

I guess we are looking for the goldilocks of peony supports.

Oops.. if the standard tomato cages aren't big enough, maybe Texas Tomato Cages will work...

http://tomatocages-com.3dcartstores.com/product_index.asp