Hello. This is an inexpensive (can be under $20, and recyclable) plastic box for a cat to sleep and rest in. This is good for indoor or outdoor cats. You could use it for an office or shop cat. It could also be a toy for children with stuffed animal toys, maybe even to encourage them to pick up toys.
You can find the bins at WM or TGT retail stores, for about $5-15. The cat's own breath and body heat can warm it in the winter, and if kept inside in an air conditioned place, the bin can remain comfortable at room temperature, yet isolate the cat from drafts and many noises, for its peace of mind. You can see if the cat is inside, if you use a clear plastic bin. If you like, you can add LED lights, stickers, marker drawings, or other art forms to customize your cat's new home.
Step 1: Tracing the Door
You need a clear plastic tote with locking handles ($5-15 at major retail stores like WM), a soldering iron ($4-10) and/ or hobby knife ("Exacto knife"), duct tape, a feed bag or dog/cat food bag, a towel or old blanket, and a magic marker. A lid the size and shape of the desired doorway will help a lot, but you can make do without by marking points and connecting the dots, using rulers or other household objects for a template.
Make the door tall and narrow, and just barely big enough for the cat. You need the bottom to be a few inches from the floor, especially for outdoor use (rain will get in if it's too low). You can expand the hole later if the cat does not fit or grows larger.
Use a template to outline your door shape, and score with the hot iron or knife. Make scoring marks or cuts first, before cutting all the way through.
The soldering iron will behave a lot like a hot glue gun, but it's like the bin is made of glue, instead of gluing something. Draw the tip at an angle, so the point is trailing the mark or cut.
Be careful not to breathe the fumes, and handle any knives very carefully!
Step 2: Cutting the Door
Carefully work your way around the cut, moving or rotating the box as necessary. Use the hot iron barrel to smooth the edges. (protect your pets, and prevent cracks).
Edit: (photo added of larger doorway)
Make sure the door hole is large enough for the cat to comfortably move in or out rapidly. My larger of two cats sprung out of the cat coop to run off the goofy chicken, and cracked the narrow doorway. I just traced a larger but similar shape outside of the crack and cut it out. Now the cats play in the box much more often and take naps in there.
Some plastic boxes have more of a projection from the handle area, to cover the doorway from rain. You can glue or tape waxed cardboard or plastic pieces over the doorway to make a rain awning, if you like.
Be creative! My child likes putting stickers all over the box, and it seems to entertain the cats!
Step 3: Adding Padding and Heat Reflective Pillow
Cut the ends off a dog food bag, and wash and dry the bag. Cut the bag to fit with the edges rolled over and taped. It makes an airy pillow pad that reflects body heat to warm the pet.
Add a comfortable towel, or old blanket, shirts, whatever cloth items your cat can use for bedding.
Put a little bit of cat nip in the cat hutch, if your pet likes cat-nip. Or you can put some other small treat in there.
Put your pet inside from the top and comfort it, so it knows it is allowed in the bed. When it's ready, put the top on, and let it come out the doorway. If it does not fit through the doorway, let it play inside and come out the top, then re-cut the hole (with all padding and bedding removed).
Get your pet used to the hutch, so it can go in and out the door.
Put the hutch where you want it to stay, and put some kind of weight in or on the box. You can put a couple old bricks in it, or a board on top of it, etc, to prevent the wind from moving it away.