I used to have hay racks but knocked that on the head recently purely because no matter what I put behind them hay would fall and build up behind the cage, which doesn't sound bad but it is when u have a two storey c&c that's difficult to move!
So now I get a box, cut an arch in each side, up turn it and fill it with hay. I get the boxes from
work in abundance as tgeyre printer paper boxes but each box lasts a few weeks anyway! I tried rabbit litter trays but they kept peeing in them but for some reason they don't pee in the card boxes?!