Although you could set up a full-size human hammock for your cat to use, you may want to buy or make a hammock specifically for your cat (it's cheaper and takes up a lot less space). A cat hammock may or may not actually resemble a hammock as humans have come to know them.
A "true" hammock rocks back and forth. Just like a human, your cat can take some time before getting the hang of it (watch the video above).
The short video above shows how the Pet Magasin hammock is assembled.
The cat hammock above is actually attached directly to hooks on the stand instead of swinging from the ropes, providing better stability than a "true" free-swinging hammock.
This anti-sway feature makes it more stable and easier for your cat to use.
The above video shows what the hammock looks like going from the box to fully assembled.
Cat hammocks generally consist of two components: 1) a stand or frame and 2) some material that gets attached to that stand or frame. Most cat hammocks don't actually sway as a "true" hammock would. Instead, the material is held up by a fixed frame and gives under the weight of your cat. This not only provides an interesting surface for your cat to lay on but can also, depending on the material, provide an airflow underneath your cat.
Cat hammocks begin to look less like hammocks when all four corners of the material are attached to the stand or frame.
A hammock can be part of a cat tree.
Yet another version raises the cat condo off the floor and adds a platform above the hammock.
A hammock can also be attached to a wall like a shelf.
Or it can include a raceway to make it easier for your cat to get to the hammock.
Or it could be part of a larger wall-mounted playground.
Cat hammocks can also appear in the form of window perches.
Just make sure the window glass where the perch is placed is solid (the glass could shatter or pull out from the weight of your cat if it's cracked or cheap and thin or poorly secured to the window frame).
You can also just buy a hammock without a stand or frame. This sort of hammock attaches to some existing frame such as a cage, a chair, or anything else you can hook or strap it to.
Do-it-yourself (DIY) cat hammocks begin with building a stand or using something that can act as the stand. The easiest way to build a stand is to use PVC or wood. Alternatively, you can use existing structures to hold up the hammock such as baskets, boxes, stools or tables turned upside down, etc.
Some DIY hammocks require you to cut and sew or glue the hammock material while others may not (some simply have you attach the material as is or cut up and tie the material). For some hammock plans it helps to have access to a sewing machine that you are comfortable using.
Below are a number of videos that show you various ways to make a cat hammock. You can follow a video to make your cat hammock or simply use it to get some other ideas. Some are simple but are more functional than ascetically appealing, while others are more complicated but produce a more appealing result. Personally, I'd rather just buy something already made (given the cost of the materials and time involved), but if you're short on cash but not time, enjoy creating something of your own, or find what you want is simply not available to buy then a DIY hammock may be for you. You can find many more cat hammock projects by doing a web search for "DIY cat hammock".