I moved into my new apartment a few months ago on the sixth floor with a good sized balcony.

In our previous apartment, we had an olive coloured wire net that we hung up so that cats couldn't fall out. It was a student apartment so we could not drill or install windows. There were a number of issues with the net solution. First, it was really ugly in my opinion and I really hated it. To top it off it wasn't all that secure. And it didn't even prevent my cats from jumping up on the railing. One of the cats would attempt to lay on the railing with her body weight away from the balcony as if it were a hammock.

We could not have the door (or windows for that matter) open unless we were closely watching them so of course we would, but sometimes they would jump up anyway when we turned our backs or if they saw a bird or insect and got excited.

We need a way to air out the apartment in case something is smoky in the kitchen and during summer evenings. This new balcony is particularly difficult because of its shape and because the door doesn't close from the outside.

Our options:

1. Inglasa the balcony (install balcony windows). We got a quote for the cost of this, but we found out that our building stopped allowing this for some reason, even though there are a number of balconies with glass installed.
2. Set up a net in the most aesthetically pleasing, yet secure way possible with a transparent net. Although, I read really bad reviews about the transparent net as they are flimsy.
3. Install an extra door on the balcony doorway with a metal bug net that can be opened and closed from the balcony side. We wouldn't allow the cats out on the balcony unless they were on leashes. This option allows us to be a bit more relaxed with not having to watch them closely while we air out the apartment and we could enjoy the balcony without an ugly net (albeit with cats on leashes or not out on the balcony).

I am leaning toward the last option. Obviously, my first is to install windows because that is the most aesthetically appealing and secure option, but that is not allowed as of now.