Quick answer: A DIY cat tunnel system for a multi-cat home links three or four moving boxes end to end along a wall, with openings big enough for your largest cat and at least two ways out of every section. Join the boxes with folded flaps and paper fasteners rather than tape, so no cat can be cornered and nothing sticky is left to chew.
Moving boxes make good tunnels: they are free after a move, sturdy enough for cats to run through and easy to replace. In a home with one cat almost any layout works. With two or more cats, the layout matters as much as the build, because a tunnel with one way in and one way out can become a place for one cat to trap another.
This build takes under an hour with boxes you already have. It covers which boxes to use, how big to cut openings, how to join sections without tape and how to lay the system out so every cat can come and go as it likes.
What You Need for a DIY Cat Tunnel System
- Three or four medium moving boxes of similar height and width.
- A box cutter or strong scissors and a ruler.
- A pencil and a dinner plate or bowl to draw round openings.
- Paper fasteners (split pins) or cotton twine for knotting inside the box walls, trimmed short.
- Plain paper or an old towel for the floor of one section.
Strip every box first. Remove packing tape, labels, staples and plastic pockets, and recycle any box that smells of chemicals or has been damp. Our guide to tape, ink and staples to avoid in cardboard builds covers what to look for.
Sizing Openings for the Biggest Cat
Measure your largest cat at the shoulder and across the chest, then draw openings comfortably larger than both. A cat should be able to walk through with its head up, not squeeze. Cramped openings slow cats down and make it easier for one to block another.
Draw round a plate or bowl to keep the edges curved, then cut slowly. Smooth any rough edges by folding them back or rubbing them with the side of the scissors. Square corners tear faster and can catch fur.
Joining Sections Without Tape
- Stand two boxes end to end and cut matching openings in the touching faces.
- Fold the flaps of one box outwards so they overlap the next box.
- Push paper fasteners through both layers at each corner and open them on the inside of the wall, pressed flat.
- Repeat for each joint, then check from inside that no metal tips are exposed.
- Leave the top flaps closed and folded in so the roof stays firm.
If you prefer no metal, punch two holes through both layers and tie them with cotton twine, knotted tight and trimmed right back. Avoid long tails that a cat could chew.
Two Exits Per Section for Multi-Cat Homes
Every section should have at least two ways out: the joint to the next box and a side opening or roof hatch. In a multi-cat home this is the most important rule. A cat inside should always be able to see a second route if another cat appears at the first.
International Cat Care advises spreading resources around the home in separate locations in multi-cat households, so cats do not have to pass each other to reach them. Treat the tunnel the same way. Run it along a wall rather than across a doorway, and keep it away from food bowls, water and litter trays.
| Layout | Works for | Watch for |
|---|---|---|
| Straight run along a wall | Most homes | Each section still needs a side exit |
| L-shape around a corner | Larger rooms | Corner box needs a roof hatch |
| Short run between two rooms | Shy cats who like cover | Keep both ends open |
| Closed loop | Not recommended | Easy for one cat to guard |
Where to Put the Tunnel
Place the tunnel where cats already travel, such as along the back of the sofa or under a window, so it becomes part of their route instead of a dead end. Keep it clear of the main path to the litter trays. International Cat Care suggests providing hiding places as well as high places for cats, and a tunnel is a hiding place on the ground.
Add an exit near something tall, such as a cat tree or shelf, so a cat can leave the tunnel and climb straight up. Cats that feel cornered on the floor often relax once they have a way to get higher.
Introducing the Tunnel
Set the tunnel up when the cats are calm, such as after a meal, and let them find it on their own. Drop a few treats just inside each opening, not deep in the middle, so no cat has to commit to a long dark stretch on its first visit. Leave the room or sit quietly at a distance.
Do not lift a cat into the tunnel or block an exit to make it go through. Cats that choose to explore come back; cats that feel pushed often avoid the whole area. Expect the bolder cat to go first and the shy cat to watch for a day or two before trying it.
If one cat has a habit of chasing another, introduce the tunnel to each cat separately at first, with the other shut in a different room, and bring them together only once both use it happily.
Playing With More Than One Cat
Tunnels are good for chasing games, but play each cat on its own as well as together. International Cat Care notes that in multi-cat homes cats should be played with individually. Pull a wand toy slowly through one section for one cat while the others are elsewhere, then swap.
International Cat Care also describes pulling a toy through a tunnel as a way to keep play varied. Use a toy with a stiff wand and keep the string under your control; put it away after each session.
Reading Your Cats in the Tunnel
- Both cats run through and out, tails up: the layout is working.
- One cat sits at an opening and the other will not go in: add an exit or move the tunnel.
- Swiping or hissing at the joints: separate sessions for a while and widen the openings.
- One cat sleeps in the middle section: that cat may want a hiding spot of its own; add a separate box elsewhere.
If one cat consistently guards the tunnel, take it down for a week and add more hiding places in different rooms first. Our multi-cat layering guide covers how to spread scratch and rest spots so cats share space more easily.
Replacing Worn Sections
Check the tunnel every few days. Replace any box with soft corners, chewed edges or damp patches; boxes are free, so there is no reason to keep a weak one. Because the sections join with fasteners, you can swap a single box without rebuilding the whole run.
Keep a spare box of the same size flat behind the sofa. Replacing a section in five minutes keeps the tunnel in good shape without a full rebuild.
More Cardboard Builds for Multi-Cat Homes
For a bigger project, our cardboard castle from moving boxes build uses the same boxes, and the multi-cat cardboard castle version adds levels and extra exits. Our cardboard castle safety checklist applies to tunnels as well.
For the full range of box builds, see the cardboard castle and box enrichment hub, and for toys to use inside the tunnel, the DIY cat toys and puzzle feeders hub.
Moving Box Tunnel FAQ
How many exits should a cat tunnel have in a multi-cat home?
At least two per section: the joint to the next box and a side opening or roof hatch. That way a cat inside always has a second route if another cat appears. Avoid closed loops, which make it easy for one cat to sit at the only exit and guard it.
Can I use packing tape to join the boxes?
It is better not to. Tape can be chewed and swallowed and leaves sticky patches that pull fur. Overlap folded flaps and fix them with paper fasteners opened flat on the inside, or with cotton twine knotted tightly and trimmed short. Check inside for any exposed tips before use.
How big should the tunnel openings be?
Bigger than your largest cat's shoulders and chest, so it can walk through with its head up. Draw round a plate or bowl to keep curved edges, cut slowly and fold back rough edges. Cramped openings slow cats down and make it easier for one cat to block another.
Where should a cat tunnel go in the home?
Along a wall on a route cats already use, away from food, water and litter trays. Put one exit near a cat tree or shelf so a cat can climb straight out. Keep it out of doorways, where it can block movement between rooms for every cat.
