you’ve got tons of options, really! you could probably just go to amazon or some other online store and buy one that was actually made for rabbits, guinea pigs, chinchillas, etc. that’s if you have access to a tiny bit of cash and if you don’t want anything DIY. otherwise, you have tons of options for hay racks you can make yourself.
the hay rack in my rabbit’s cage area was one i bought off of amazon. it’s a little bit of an annoyance for both me and her, however, because she tends to ignore the front tray (where i move all of the old stuff into) and go for the back where she sometimes struggles to reach through. she also can’t reach the stuff at the very bottom of the back part and therefore i have to reach my hand in and pull it out. i’ll be getting a new one soon (as well as a new litterbox) so i’ll link both here.
another thing i’ve tried is using one of those dollar store…i think they’re CD bins or something? i’m not really sure, but they’re just plastic boxes with open tops and holes all over the sides. with something like this you’d still have to push hay through, though, not to mention that if you don’t install a piece of cardboard on the bottom like i did, you’ll end up with a huge mess when you move it to a different spot. also, i had trouble figuring out how to place it. my rabbit could jump into it (and has peed in her hay multiple times because of this), but when it’s upside down and covered on the open top she can’t easily get to her hay and it’s a bit tricky for me to refill it.
i’d say your best bet would be to buy a good one. i’ll link my old and new hay rack here.

old one (keep in mind this isn’t the exact one but this is a similar model): https://www.amazon.com/Kaytee-Food-Feeder-Quick-Locks/dp/B005FU4Z8I/ref=sr_1_12?ie=UTF8&qid=1500331711&sr=8-12&keywords=rabbit+hay+rack

new one: https://www.amazon.com/dp/B0006L2VYG/ref=ord_cart_shr?_encoding=UTF8&psc=1&smid=ATVPDKIKX0DER

it’ll all depend on your preference and specific setup.

hey. on several places on the internet, you can buy handmade wooden hayracks.l they may be a bit more expensive, but support other bunny owners. also they look nice and bunnies love them.

I stuff hay in toilet rolls. If you pack it tight it’s hard for them to make a mess, and you can give them as many toilet rolls as needed to ensure 24/7 hay. They can also carry it around a bit that way too, which mine seem to enjoy.

ive tried way too many to list- wooden ones, toilet rolls, loose in tray , diy ones , wire ones , repurposed ones , shower caddys and more.

for one reason or an another i always ran into a problem – then sitting in hay meaning it gets weed on , it not pushing out to the sides after some consumption meaning i need to pull it out , not holding enough and so on 

the best i have found ( and now i will never switch from ) are the simple ones that come with cages alot of the time

it falls into right place as they consume some , they cant pee in it , holds enough for my boys for the day ( they are holland lops – when i had flemish giants i used two per cage) , can fit over litter tray , can attach to playpen / cage/ nic grid 

You can make your own hayrack our Of wood, or just use a cardboard box attached to the wall or cage. I use a diy hayrack that I made out of a paper bag, but my bunnies also eat the hay I use as bedding.