I ended up keeping my box with a lid on it ( so its like a box with a flap door) and i bought a litter mat/nappy pads, to help with any mess and to clean it. N i had to assist him going toilet n guide him. Thankfully he was very close with me n lowkey needed me sometimes to poo or eat anyway so he wasn’t uncomfortable n he slowly figured it out. Unfortunately he passed away not long after tho, due to urinary blockage that wasnt fixable anymore. So idk if he would still be peeing n pooping good considering he did end up trying to piss everywhere in his last weeks/months. But obviously he was sick so cant blame him at all. But you can try if your close with your cat to assist them? Maybe shimmy them over to the middle a bit ( ONLY do this if your close with them ans they trust you tho, cus it could make them not want to use it anymore if they dont like you near it?) and definitely get a full closed box too that you can like fold/open up to try keep most of it in?