Quick answer: A DIY tunnel system from moving boxes takes under an hour if every segment is built the same way: four similar boxes, matching round ports about 18 cm across at each end, and joins made with paper tape or clips rather than staples. Because the ports match, you can rearrange the segments into a new layout every week.
After a move, most homes have a stack of boxes and a cat already sitting in one. A single box is good for an afternoon. A row of boxes joined into tunnels gives a cat somewhere to stalk, hide and ambush, and costs nothing.
The trick to keeping it interesting is making it modular. If every box has the same size holes in the same places, the tunnels can be rearranged in a few minutes. This guide builds four standard segments and gives three layouts to rotate, so the system feels new each week without building anything else.
Why Tunnels Rather Than Another Box
Cats like to move under cover. A tunnel gives them a hidden route through a room, which suits shy cats and playful ones alike. International Cat Care suggests placing items such as cardboard boxes or paper bags around the home and leaving the cat to decide whether they are worth exploring, and also recommends rotating toys so they stay interesting. A tunnel system does both.
It also uses floor space differently from a cat tree. Tunnels run along a wall or behind the sofa, low and out of the way, and fold flat when you need the room back.
Choosing and Preparing the Boxes
| Box | Size (approx.) | Use |
|---|---|---|
| Medium moving box | 45 × 30 × 30 cm | Standard tunnel segment |
| Same size box, uncut top | 45 × 30 × 30 cm | Hideout with a single port |
| Large box | 60 × 40 × 40 cm | Junction for a T layout |
Pick four boxes of the same size for the main segments; matching sizes make the joins easy. Remove every staple, plastic tape strip and label. Our guide to tape, ink and staples to avoid in cardboard DIY explains which materials to strip before a cat uses a box. Avoid boxes that held chemicals or smell strongly.
DIY Tunnel System Build: Four Segments
Each segment is a box lying on its side with a round port at each end. Draw the ports with a plate or a bowl of about 18 cm diameter, centred and with the bottom edge about 5 cm above the floor of the box so the box keeps its strength.
- Seal each box closed with paper tape, then lay it on its long side.
- Draw an 18 cm circle on each short end, 5 cm up from the bottom.
- Cut the circles with a craft knife, adult hands only, and smooth the edge by folding a strip of paper tape over it.
- Cut one extra 18 cm port in the middle of one long side on two of the boxes; these become the junction pieces.
- Mark the top of every box with an arrow so you always join them the same way up.
| Task | Time |
|---|---|
| Strip staples and tape, four boxes | 10 minutes |
| Draw and cut 10 ports | 25 minutes |
| Edge the ports | 10 minutes |
| Join the first layout | 10 minutes |
| Total | 55 minutes |
Two boxes with two end ports each and two boxes with a third side port gives 4 + 6 = 10 ports. The timings add up to 55 minutes, inside the hour, with some slack for a cat inspecting your work.
Joining Segments Safely
Push two segments together so their ports line up, then hold them with large binder clips on the top edges or a strip of paper tape around the joint. Paper tape is easy to remove and does not leave a sticky surface for paws. Do not use staples, which can come loose, or plastic packing tape, which a cat may chew.
Weight the ends with a book on top if the tunnel shifts when the cat runs through. On hard floors, a rug underneath stops the whole line sliding. Check the joints each time you change the layout and replace any segment that is crushed or damp.
Three Layouts to Rotate
| Layout | Segments used | Length | Best for |
|---|---|---|---|
| Straight run | 4 in a line | About 1.8 m | Fast chasing, along a wall |
| L-turn | 2 + 2 at a junction | About 0.9 m each way | Behind a sofa corner |
| T with hideout | 3 in a line + hideout on the side port | About 1.35 m plus the hideout | Shy cats, ambush play |
Four 45 cm segments in a line make about 1.8 m. Three make about 1.35 m. Rotate weekly: straight run on week one, L-turn on week two, T with hideout on week three, then start again. Ohio State's Indoor Pet Initiative also suggests rotating a few toys at a time, which pairs well with changing the tunnel; put one toy inside a new layout each week.
Play Ideas for Each Layout
In the straight run, drag a wand toy past the far port so the cat races through. In the L-turn, roll a ball from one end so it disappears around the bend. In the T layout, drop a few treats in the hideout and let the cat find them through the side port.
Keep sessions short and end with a catch, so the cat finishes with a win. Never leave string toys inside the tunnel unattended; take wand toys out when play ends.
Adjusting Segments for Different Cats
The standard 18 cm port and 30 cm height suit an average adult. Change them for cats that do not fit the average.
| Cat | Change | Why |
|---|---|---|
| Kitten | Smaller ports, about 14 cm, and a shorter run | Feels safer and stays easy to explore |
| Large breed | Ports about 22 cm, taller boxes | Room to turn without crouching hard |
| Senior or stiff cat | Two segments only, port bottoms at floor level | No step over a lip, short distance |
| Nervous cat | T layout with hideout, placed against a wall | Cover on one side, a retreat at the end |
For a senior cat, cut the ports down to the floor of the box and reinforce the cut edge with a double layer of paper tape, since the box loses some strength there. Watch the first few sessions; if a cat hesitates at a port or turns back, widen it rather than coaxing it through.
Storing and Refreshing the System
Between rotations, you can stack segments inside one another if you cut them slightly different sizes, or simply stand them against a wall. Replace any segment that gets damp, chewed through or smelly. Cardboard is cheap; a fresh box keeps the system hygienic.
If you have more than one cat, add a second exit to each layout so nobody gets trapped. The multi-cat cardboard castle guide covers exits and spacing, and the cardboard castle safety checklist applies to tunnels too.
Where to Take It Next
Once tunnels are a hit, add height. The cardboard castle from moving boxes in under an hour uses the same boxes upwards, and the castle rotation system shows how to swap towers and rooms. Families can turn it into a project with the kids and cats cardboard castle weekend build.
For more cardboard ideas, see the cardboard cat castle and box enrichment hub.
Cardboard Tunnel Questions
How do you make a cat tunnel from moving boxes?
Use four boxes of the same size, remove staples and plastic tape, and lay each on its side. Cut an 18 cm round port at each end, about 5 cm up from the bottom, and edge it with paper tape. Line the ports up and join the boxes with binder clips or paper tape.
How big should the holes be in a cardboard cat tunnel?
About 18 cm across suits most adult cats, cut with the bottom edge roughly 5 cm above the floor of the box so the box keeps its strength. For a large cat, measure across the shoulders and add a few centimetres. Keep every port the same size so segments can be rearranged.
How often should I change my cat's tunnel layout?
Once a week works well. Rotate between a straight run, an L-turn and a T with a hideout, and add one toy to each new layout. Ohio State's Indoor Pet Initiative suggests rotating a few toys at a time, and changing the tunnel shape keeps it new in the same way.
Is cardboard safe for cats to play in?
Plain cardboard is generally fine. Remove staples, plastic tape and glossy labels, and avoid boxes that held chemicals or smell strongly. Join segments with paper tape or clips, check for damp or chewed sections, and replace damaged boxes. Take string or wand toys out when play ends.
