Cats are free spirits; anyone who plans to keep one in a kennel as permanent housing will end up with a very unhappy feline displaying either signs of depression or reversion to the wild side. There are times, however, when even the most civilised cat needs a "time out" for his own good. A homemade kennel makes a safe place for him to "chill" or spend a day when the human has to be away on business.
Start with some behavioural observation. Your cat does not respond to the kennel-as-den the way your dog does. Determine whether he likes sleeping on the bed near a sunny window or parks next to the shoe rack in the closet; whether he prefers to relax on Grandma's hand-knitted coverlet or a freshly-laundered stack of underwear; or whether he patrols the house on the floor or enjoys airborne patterns, jumping from counter to cabinet top. These behaviour patterns will inform your choices as you design your cat kennel.
Build a sturdy frame for your kennel using 1-by-2-inch or larger lumber, depending on how big your kennel will be. A spacious kennel with a 4-by-4-foot base that stands 5 feet tall will make a perfect "motel" room. Build four 4-foot squares and connect three of them with uprights on the inside. Reserve the fourth square to make a top for the kennel. Reinforce tall kennels with extra lateral bracing every 3 feet or diagonal "Z"-bars. Keep bracing on the outside so vertical members can support interior structures.
Furnish your cat's kennel, which will serve as her temporary home, with her habits and preferences in mind. Add plywood perches cover covered with carpet scraps across the kennel at different levels to provide steps for play and scratching that also protect paw pads and mouths from splinters. If you have a climber, attach an upholstered pole diagonally across the kennel for "cat crazy" time. Before attaching perches and "trees," sand edges and varnish or paint the entire frame with nontoxic paint (the kind recommended for children's toys). Allow the paint dry completely before permanently installing the amenities.
Wrap vinyl-coated welded wire (available at home and hardware stores) around the kennel and secure it along the uprights with heavy staples or brads. If vinyl-coated wire is not available, make your own using galvanised welded wire and vinyl paint. Vinyl paint requires a two-step process, so allow plenty of time if you have to do the painting yourself. Use 14 gauge wire and buy fencing that has openings no larger than 2 by 3 inches. Many cats can get through---or get stuck---in larger weaves. If you have kittens, use the 1-by-1-inch weave; kittens have an amazing capacity for getting halfway through almost anything. Add a door to the top of the kennel by covering the fourth 4-by-4-foot square with fence wire and attaching it to the top of the frame with a piano hinge. Add a hook or padlock latch to the opposite side to prevent escapes.
Equip the kennel with a cat bed or carpeted pad and with food, water dishes on a mat (boot mats work well) and a litter box in the bottom of the kennel. Position the kennel by a sunny window or in the between rooms where she can see everything---wherever she'll be happiest.
If your cat's an escape artist (or a kitten with no sense whatsoever), fill any spaces between horizontal wood frames and fencing wire by fitting a second piece of wood to the upright between the horizontals and staple wire along all parts of the frame. Even if he's a lazy guy, staple the wire to the uprights as well as the horizontal parts of the frame so Max can't get his head stuck between the wire and the frame.