Hello! You can put a roof on a c and c cage!
Here’s a link to that on the cages store. I’m sure you could also just make a lid by using hinges. Here’s a video on how to make one yourself.
www.youtube.com/watch?v=m6qKkeYgbcI
For how many cubes you’ll need, it depends. According to the reviews it says that the cubes are approximately 14 inches wide. The grids that they sell from the guinea pig cages store are 14 inches, and a 5 by 4 grid cage is 76 inches by 30 inches. Since the Amazon basics c and c grids aren’t exactly the same as the cubes that the guinea pig cages store sells, the measurements might be a bit off. Another option would just to buy the grids directly from the guinea pig cages store.
Those grids (if I’m looking at the right listing) look to be fine. You just want to watch out for grids that are only divided into six squares.
About the hay. You could use kaytee brand, but I don’t recommend it. It’s usually not very fresh and it’s expensive. I like to buy my hay in bulk off of Amazon. I’ve been buying
this brand of hay for years and it’s always green and fresh. It’s also a lot cheaper than buying multiple bags from the pet store. Although that being said, you’ll need a spot to store all that hay. The box it comes in is HUGE! So if you live in an apartment, then you might need to buy hay in smaller packages.
By the way, you guinea pigs are ADORABLE! Bubbles looks like a guinea pig that I fostered.