Quick answer: A cat tunnel system from moving boxes links three to six boxes through round or arched openings about 20 to 25 cm wide, joined with paper tape or tabs rather than staples or plastic tape. Before each play session, check every join for loose tape, exposed staples, crushed sections and sharp edges, and replace any box that is soggy or chewed.
After a move, the flat is full of boxes and the cat is usually already inside one of them. That instinct is worth using. A connected run of boxes gives a cat somewhere to hide, ambush and race through, and it costs nothing but an afternoon.
The weak points of a box tunnel are the joins: tape, staples, cut edges and the places where one box meets the next. This guide builds the system with those joins in mind and finishes with a checklist to run before each session, so the tunnel stays fun and safe for as long as the cardboard lasts.
Planning a Cat Tunnel System From Moving Boxes
Start with what you have. Medium moving boxes, roughly 45 cm on a side, suit most cats; small book boxes work for kittens or as short connectors. Lay them out on the floor first to try different shapes before you cut anything.
| Layout | Boxes | Best for | Floor space |
|---|---|---|---|
| Straight run | 3 to 4 | Racing and pouncing | Along a wall |
| L-shape | 4 | Corners and hiding | Room corner |
| T-junction | 4 to 5 | Ambush games with two cats | Middle of a room |
| Loop | 5 to 6 | Chasing without dead ends | Larger floor area |
Avoid long dead ends where a nervous cat could feel trapped. A tunnel with at least two exits, or a peep hole partway along, lets a cat leave the way it chooses.
Preparing the Boxes
Strip off all plastic packing tape, shipping labels and any staples before you start. Plastic tape and staples are the main hazards in moving boxes. Cut away flaps you do not need, and set aside boxes that are damp, stained or smell of whatever they carried.
Our guide to tape, ink and staples to avoid in cardboard DIY explains which materials to remove and why. If a box has heavy printing on the inside, turn it so the plain side faces in, or use it as an outer section.
Cutting Openings and Joining Sections
- Mark a circle or arch about 20 to 25 cm wide on the end of each box where it will meet the next one.
- Cut with a sharp craft knife, keeping the blade away from your hand.
- Rub every cut edge with sandpaper or fold a strip of paper tape over it.
- Line up openings and join boxes with paper tape or slot-together tabs.
- Add a few round peep holes along the sides, about the size of a cat's paw.
- Weigh down the end boxes with a book inside a sealed outer flap if the run slides.
Make the openings wide enough for your largest cat to pass without squeezing. Large breeds may need 25 to 30 cm. Gummed paper tape, the kind you wet to activate, holds well and is far less tempting to chew than plastic tape.
Why Joins and Loose Material Matter
A tunnel is mostly safe cardboard, but the small bits are a real concern. VCA Animal Hospitals' article on foreign bodies in cats lists paper and rubber bands among items cats commonly swallow, and explains that string and thread are especially dangerous. Peeling tape strips and frayed cardboard edges are the parts a cat is most likely to chew, so they need regular checking.
Never hang toys inside the tunnel on string or elastic, and do not leave the tunnel out with toys attached while you are away. A toy dropped loose inside is fine.
The Pre-Play Safety Checklist
- Every join is firm and the tape is flat, with no loose ends.
- No staples, plastic tape or labels remain anywhere.
- Cut edges are smooth or covered.
- No section is crushed, soggy or sagging.
- Openings are wide enough for every cat that uses it.
- The run does not slide when a cat dashes through.
- There are at least two ways out.
- No string, elastic or small loose parts are inside.
This takes under a minute. Doing it every time you bring the tunnel out keeps small problems from becoming chewed tape in your cat's stomach.
Making the Tunnel More Engaging
Cats like places to hide and spots up high, as International Cat Care explains in its guide to making your home cat-friendly. Add a box on top of one section with a hole cut down into the tunnel, and the run becomes a lookout as well as a hideout. A folded towel in one box gives a resting spot.
Play with your cat around it. Drag a wand toy past the openings so it can pounce out, or drop a treat into the far end. International Cat Care's guide on play points out that cats enjoy stalking, chasing and pouncing, and a tunnel with peep holes is made for exactly that. For a quick build to add on, try our 30-minute cardboard castle or the cardboard castle from moving boxes.
Adjusting the Build for Kittens, Seniors and Pairs
Kittens are small enough to squeeze into gaps you did not intend as openings, so close every unused flap and check that no join leaves a slot a kitten could wedge itself into. Keep the run low and short at first, and supervise until you know how your kitten uses it.
Older or stiff cats prefer a tunnel they can walk through rather than crawl. Use taller boxes, cut arched doorways right down to floor level so there is no lip to step over, and skip the stacked lookout boxes. A soft towel in the middle section gives them somewhere to rest halfway.
For two cats, a loop or T-junction works better than a straight run, because neither cat can corner the other. Watch the first sessions: chasing in turns is play, while one cat repeatedly blocking an exit is a sign to add another way out.
When to Retire a Section
Cardboard wears out. Replace a box when it is soggy, chewed through, crushed so the opening narrows, or smells of urine. Because the system is modular, you only need to swap that section.
| Sign | Action |
|---|---|
| Corners soft or sagging | Replace that box |
| Tape peeling at a join | Re-tape or replace |
| Chewed holes or loose flaps | Trim or replace |
| Soiled or smelly | Replace and recycle |
Most box tunnels last a few weeks to a couple of months, depending on how hard they are played with. Storing it flat-packed when not in use helps it last longer and keeps it novel.
Rotating the Tunnel With Other Cardboard Projects
A tunnel is most exciting when it is new. Bring it out for a few days, then flat-pack it and replace it with another cardboard project for a while. Our cardboard castle rotation system and rotating DIY toys guide show how to plan that kind of schedule, and the cardboard castle and box enrichment hub has more builds. At CozeCats, we like enrichment that uses what is already in your home, and moving boxes are one of the best free materials there is.
Questions About Cardboard Box Cat Tunnels
Is it safe to use moving boxes for cat toys?
Yes, if you remove all plastic packing tape, labels and staples first, smooth or cover cut edges, and avoid boxes that are damp or smell of chemicals. Join sections with paper tape or tabs and check every join before each play session. Replace any box that is chewed, soggy or soiled.
How big should the openings in a cat tunnel be?
About 20 to 25 cm wide suits most adult cats. Large breeds such as Maine Coons may need 25 to 30 cm so they can pass through without squeezing. Make every opening in the run wide enough for your largest cat, and add a second exit so no cat feels trapped.
What tape is safe for cardboard cat toys?
Gummed paper tape, the kind you wet to activate, is a good choice because it holds well and is less tempting to chew than plastic tape. Keep tape flat with no loose ends. Avoid plastic packing tape and staples, which can be chewed off or leave sharp points.
How long will a moving-box tunnel hold up?
Usually a few weeks to a couple of months, depending on how hard your cat plays. Because the tunnel is built from separate boxes, you can replace just the worn section. Flat-packing it between play sessions helps it last longer and keeps it feeling new.
