There are many, many options and you need to consider whether you have an indoor cat or an outdoor cat and also what amount of money are you willing to pay towards the goal of establishing an outdoor space for your cat?
One of the popular brands of pet enclosures is Kittywalk, which offers you light weight, movable units that you can combine in different interesting patterns for your particular yard. They are made of tubular steel frame and netting and use ground pegs and ties for their hammocks and attaching units together. The manufacturer recommends that your cats be supervised in these enclosures. These modular units are suited to ‘indoor’ cats. They range in prices from $80 to $400 for one unit, depending on how large they are.
Cat’s Den offers quality kits in a variety of designs that are reasonably large and sturdy spaces for cats to independently go in and out of, when you set it up with a cat door to the space. They are made of strong galvanized or black coated steel and include cedar floor boards and shelves for your cat to climb and lounge on. These kits range in price from $900 to $4000.
Purr-fect Fence offers fencing containment options of two varieties…one is a free standing fence enclosure and the other is an extension for existing fences. This fence is made of a type of flat plastic fencing that is called deer fence. Purr-fect fence has designed a spring loaded lever to discourage climbing cats and to keep cats inside the space. The cost depends on the yard space that you want to enclose How many extension kits are needed to enclose the space? An extra large yard would cost about $1000 to fit with extensions. A cat used to his outdoor freedom would likely be happy in a full yard space.
There are other options that you could consider, including various homemade varieties that could be made from wood posts and chicken wire or other types of fencing, in addition to netting.
Further containment fencing considerations include whether you need to abide by any fencing bi-laws that could restrict the height of the fence. For example, I live in a city area where there is 6’2″ height restriction.
In summary, think about what amount of money you are willing to spend. Then decide on what amount of space you want to enclose, given the type of cat(s) that you have. Consider your options and whether you want to go for a manufactured kit or be creative and industrious in finding and buying the materials needed to make your own enclosure.