Slow feeders

This year has been horrible for crops, hay included. Until September we had less than four inches of rain since May and it was dry, dry, dry, dry. The first cutting of hay was pitiful and the others simply did not exist. So I went to buy gold hay for the old ladies, who cannot have hay off the round bales due to their allergies. Alfalfa is what they were getting and it wasn't an option. No one had any and if they did the price was astronomical. We ended up getting some decent grass bales for a decent price. The problem is the old ladies are picky and spread their less appealing grass hay in a 50 foot radius, stomping, pooping and peeing on good hay that should be eaten. So I spent a great deal of time thinking about how to feed the ladies. We thought about putting the hay in a feeder so at least it was off the ground. Knowing horses they were likely to take a huge first bite of a flake and shake it all over.
So I thought, I need a feeder that I can put hay in and they can't just take a flake out and stomp and poop and pee all over it. I have seen hay nets such as Lisa's from Laughing orca ranch but I couldn't really hang them on the shed due to the shed being pretty old and probably wouldn't fare well against daily hungry horse abuse. If they were on the ground I was afraid of them or something getting wound up in it. So I decided to go with something not only portable but durable. I didn't want to be re-making this thing.
So with my idea's and Maverick's carpenter skills (that is after all, his first trade before being a farrier) we made this: 

 It only has one coat of paint and no lid at this point. We built it completely out of scrap lumber. We literally only bought a hog panel for the sides because after thinking about the many we have on the farms they were all bent up and not worth the bother to try and straiten or fix them. I also bought barn paint for the lumber because I didn't want it to rot or have any harmful substances the horses could ingest.

We started with an old pallet for the bottom and built up from there. The pyramid for the middle keeps the flakes of hay against the sides. You can fit approximately 1 bale of hay in here. The first week I used it the ladies inhaled the hay in a couple hours. Now a week later they munch on it, pulling mouthfuls from between the bars (their teeth don't touch the hog pannel I made sure) they go away, graze, come back. There's always a little left when I come back the next feeding which is great, meaning their stomachs are never empty.

 The old ladies are also eating hay together now, rather than squabbling at feeding time over who gets the hay pile they want (Indigo).

I have another idea using the hog panel to make a V shaped one but I have yet to see round bale ones that were not hockey net. Anyone have ideas?