Cat eats all of the elderly ferrets food everyday

So I have a very ill, very elderly ferret who lives in a large playpen with no top. My young 1 yr old cat is obsessed with the ferrets food and will get in there and eat it all. It was just annoying but now that the ferret can't eat whole pieces of food I spend hours cutting each piece up individually. It's extremely tedious and time consuming. But I do it bc she chokes on who,e pieces and won't eat any other foods. Any of you have ideas on what I can cover the top of the cage with that can easily be peeled back for my access for daily playtime and to cleaning etc? Or maybe a way of having the food out for the ferret but the cat can't access?
I've tried a tarp, cat just gets in the middle and weights it down until it caves in. I also can't put the food up bc the ferret needs constant access and I'm not moving the ferret away from the family room. I'm getting so upset. It's every day and I'm losing so much food I spent work on cutting up. I take the cat with me and lock her in another room when I leave the family room but sometimes I forget or get caught up with something.
Below is a pic of the play pen. Excuse the poo, need to change the pad out lol

Chicken wire and zip ties.
Cage wire and zip ties.
Livestock PANEL wire and zip ties on one side of the cage/lid only.

The panel wire will cost the most ($35 to $50 for one panel).  Be LOTS more than you would need, and cutting the wire might not be very easy.  You might have to buy some small bolt cutters to cut it.  Which would just add to the expense.

BUT, livestock panels are very rigid, will hold the weight of any cat, and the whole panel can be moved off of the top of the ferret cage easily....or lifted up with the zip ties acting as a hinge.

On 2nd thought.  What's that cage?  7ft x 6ft?
If so, I'd go with one Livestock Panel.    You should be able to find one 10ft long and 6ft tall.  (4"x2" holes, or smaller).

If you use chicken wire, or cage wire.  You'll have to build a frame around it out of at least 2"x2" lumber... (like a big screen door).   That will keep it light enough to move/lift out of the way.