I Used Foam Board to Divide My IKEA Kallax Cubby for Wool — Here’s What I Learned

If you’ve spent any time in the fiber arts community, you already know that yarn storage is one of those problems that never fully gets solved. You find a system, it works for a while, and then somehow your collection doubles and everything falls into chaos again. That was exactly my situation about six months ago when I stood in front of my IKEA Kallax shelf and realized that the cubbies — as much as I love them — were just too big and too open for my wool stash.

The cubbies on a Kallax are 13 inches wide, 13 inches tall, and about 15 inches deep. They are perfectly sized for magazine files, fabric bins, and decorative baskets. They are not, however, perfectly sized for balls of wool that roll around, skeins that tumble over each other, or half-used cakes of yarn that you swear you set down in a specific spot. I needed divisions. I needed compartments. I wanted something that would let me see every skein at a glance without wrestling a basket out of the shelf to find what was buried at the bottom.

After a lot of thinking — and honestly, a lot of procrastinating while watching other people’s craft room tours on YouTube — I landed on foam board as my divider material. It was cheap, it was easy to cut, it required no power tools, and I already had a box cutter in my desk drawer. Here is everything that happened when I actually did it, what worked, what I would do differently, and why this approach might be exactly what your yarn storage situation needs.

Why Foam Board and Not Something Sturdier?

This is usually the first thing people ask. Why not wood? Why not acrylic? Why not those little plastic shelf dividers you can buy online?

The honest answer is that foam board hits a very specific sweet spot for a project like this. Wood would require a saw, sandpaper, possibly a drill, and real measurements taken with real precision. Acrylic sheets are beautiful but expensive, tend to crack if you score and snap them incorrectly, and have edges that need finishing if you don’t want to scratch your hands every time you reach into the cubby. Plastic clip-on dividers work well for closet shelves but they are designed for flat shelving, not the boxed, enclosed structure of a Kallax cubby.

Foam board — the kind you find at any dollar store, craft store, or office supply shop — is lightweight, has a slightly grippy paper surface, cuts cleanly with a box cutter, and can be wedged or scored so that two pieces interlock without any glue or hardware. It costs almost nothing. A single large sheet (usually around 20 by 30 inches) can divide multiple cubbies. And if you cut something wrong, you simply cut another piece. There is no waste of money or significant materials when you make a mistake.

The one legitimate concern people raise is durability. Foam board is not going to last decades. It dents if you press on it hard enough, and the paper surface can peel at the corners over time. But here is the thing: for a low-impact application like dividing yarn storage, where nothing heavy is being placed on top of it and nothing is being dragged roughly across it, foam board holds up remarkably well. My divisions are six months old and still sitting exactly where I put them.

What You Will Need Before You Start

Before you cut anything, gather everything you need so you are not stopping midway through to hunt for a ruler.

You will need foam board sheets — the standard quarter-inch thickness works perfectly for this application. You will need a sharp box cutter or craft knife, because a dull blade drags and tears instead of cutting cleanly. A metal ruler is strongly preferable to a plastic one, since the knife can veer into a plastic edge. A cutting mat or a stack of old magazines protects your table surface. A pencil for marking measurements. And optionally, a piece of fine sandpaper for smoothing any rough edges, though I found this mostly unnecessary with clean cuts.

That is genuinely the whole supply list. If you already have a box cutter and a ruler, your only expense is the foam board itself.

Planning Your Divisions Before Cutting Anything

This is the step that most people skip, and it is also the step that saves the most frustration. Before you cut a single piece of foam board, decide what you want each divided cubby to hold and how many compartments you want.

I thought through my wool stash and realized I wanted three horizontal sections within each cubby — one for sock yarn, one for DK and sport weight, and one for worsted and bulky. Within those horizontal rows, I also wanted at least one vertical divider so that colors would not bleed into each other visually. That gave me a grid-like structure within each cubby: two columns and three rows, creating six individual compartments per cubby.

You might want something different. Maybe you sort by fiber content rather than weight, in which case you might want four equal sections. Maybe you just want a single vertical divider down the middle so each cubby holds two neat stacks of yarn instead of one chaotic pile. There is no correct answer — the point is to decide before you cut.

Once you have a plan, sketch it out roughly on paper. Note the dimensions of the Kallax cubby interior: approximately 13 inches wide, 13 inches tall, 15 inches deep. Your dividers will run either vertically or horizontally, and they need to be cut to the depth of the cubby (15 inches) in one direction and to the appropriate span of the opening in the other direction.

The Cutting and Interlocking Method

There are two main approaches to making foam board dividers work inside a cubby without glue.

The first and most satisfying approach is the slot-and-tab method, which is essentially the same technique used to make cardboard model kits. If you want horizontal and vertical dividers that intersect, you cut a slot halfway through one piece at the intersection point and a corresponding slot halfway through the other piece. The two pieces slide together at the slots and lock without any adhesive. The resulting cross-shaped join is surprisingly sturdy and does not wobble.

To do this, cut your horizontal divider to the full width of the cubby interior — approximately 13 inches — and to the full depth, approximately 15 inches. Then cut a slot from one edge to the center of the board at the point where you want the vertical divider to cross it. The slot should be as wide as the thickness of your foam board, which for quarter-inch foam board means cutting two lines about a quarter inch apart and removing the foam between them. Do the same on your vertical divider, but cut the slot from the opposite edge. When you slide them together, they interlock and the cross-shaped piece sits flat.

The second approach is simpler and works well if you only want dividers going in one direction, or if you want to avoid the slot-cutting step. You cut your dividers slightly taller than the interior height of the cubby — maybe a quarter inch extra — so that they create a slight bow when inserted, pressing against the top and bottom surfaces and holding themselves in place through friction. This works particularly well for vertical dividers. The slight compression keeps them from tipping or sliding, and they are easy to remove later if you want to reconfigure.

I ended up using a combination of both methods depending on the cubby. Cubbies where I wanted a full grid got the slot-and-tab treatment. Cubbies where I just wanted a simple vertical split got the friction-fit dividers.

Tips for Cleaner Cuts

Cutting foam board cleanly is simple once you understand what the material wants. The most important thing is to score rather than saw. You are not dragging the blade back and forth — you are drawing it through the material in one or two smooth, firm passes. The first pass scores through the paper and into the foam. The second pass, if needed, completes the cut through the bottom paper layer. Trying to cut through in one aggressive stroke often results in the blade skipping or the edge tearing.

Keep your metal ruler pressed firmly against the board while you cut. If the ruler shifts even slightly, your line will shift with it. I found it helpful to put one hand on the ruler with real pressure and cut slowly rather than quickly.

Corners where two cuts meet are the spots most likely to look messy. Cut slightly past your intended corner point — just a millimeter or two — and the corner will be clean rather than rounded or fibrous-looking.

If the edge of a cut piece does feel rough or has small foam fibers hanging off it, a light pass with fine sandpaper smooths it instantly. You can also run your fingernail along the edge to compress any stray fibers back into the surface.

Finishing Touches That Make a Difference

Foam board in its natural state is white, which works fine in most contexts. But if your Kallax is a dark color — birch, oak, black-brown, or any of the other finishes — bright white dividers inside each cubby can look a little clinical and jarring.

The simplest fix is to cover the visible faces of your dividers with washi tape, contact paper, or decorative paper. Because the surface of foam board is just paper, it takes adhesive products extremely well. A roll of patterned contact paper and twenty minutes can transform your dividers from utilitarian to intentional-looking. I covered mine in a subtle linen-texture contact paper that reads as neutral in photographs and blends with the natural wood tone of my shelf.

You can also paint foam board with acrylic craft paint if you want a solid color. Use a sponge or foam roller rather than a brush, and apply thin coats — thick paint can warp the board if it saturates the paper surface on only one side. Two thin coats of acrylic in a color that matches or complements your shelf finish looks very clean.

Another small detail that makes a big difference: label each compartment. Even the most organized person forgets where they put things when a stash gets large enough. I used small adhesive labels on the front edge of each horizontal divider with the weight and fiber category written in pencil so it can be erased and updated. Some people prefer a small handwritten tag tied with twine to the front of the divider for a softer, less officey look. Either way, the labeling step is what turns a storage solution into a system.

How It Has Actually Changed the Way I Use My Wool

I want to talk about this part specifically because I was not sure how much of a difference physical organization would make to my crafting life. I expected to feel more organized. I did not expect to actually reach for yarn more often, or to find myself finishing projects that I had been stalling on.

What happened was this: when your stash is visible and sorted, it becomes a resource rather than a burden. Before the dividers, I knew I had yarn but I did not always know exactly what I had. I would dig through a cubby looking for the skein I was thinking of, not find it immediately, and then abandon the search and buy new yarn instead. Classic scarcity mindset despite actual abundance.

After dividing the cubbies, every skein is visible. I can stand in front of the Kallax and scan across it the way you scan across a bookshelf. I see exactly what weights I have, which colors are available, how much of something is left. I have used up three partial skeins in the last month that I had genuinely forgotten existed. I started a project I had been putting off because I kept thinking I needed to buy more yarn for it — turns out I had what I needed the entire time, sitting in the wrong section and therefore functionally invisible.

This is the understated benefit of physical organization: it changes your relationship to your materials. You stop managing inventory in your head and let the visual arrangement do that work for you.

Common Questions and Problems

People who try this project often run into a few predictable snags, and it helps to know about them before you start.

The most common issue is that the cubby interior is not perfectly square. IKEA furniture is manufactured to tight tolerances but not to custom-joinery tolerances, and in practice your cubby might be 13 and a quarter inches wide in some spots and 13 and an eighth in others. Measure in multiple places and cut your dividers to the smallest measurement, then use the friction method (the slightly-too-tall trick) to account for any variation. If a divider fits loosely in one spot, a small strip of foam board glued to its edge creates a shim that takes up the slack.

Another issue is that foam board has a slight flex to it when cut into long, narrow strips. A horizontal divider that spans the full 13-inch width might sag slightly in the middle if the compartment below it is loaded with heavy yarn. The fix is to cut that particular divider slightly deeper — 16 or 17 inches instead of 15 — so that the back edge rests against the back wall of the cubby, which provides support and prevents sagging. For very heavy yarn weights, you can also score and fold a small lip into the front edge of the divider to give it more structural stiffness.

Finally, some people worry about the foam board absorbing moisture and warping over time, especially in humid climates or rooms that see temperature variation. This is a legitimate concern. If humidity is an issue in your space, sealing the foam board with a light coat of acrylic medium or covering both faces with contact paper before installation creates a moisture barrier that significantly reduces any warping tendency.

Final Thoughts

This is one of those projects that sits at the exact intersection of cheap, fast, and genuinely satisfying. You do not need to be crafty to pull it off. You do not need any special tools. You do not need to watch seventeen tutorial videos before you feel ready. You need a sheet of foam board, a box cutter, a ruler, and an afternoon.

The result is a Kallax that finally works the way you always hoped it would — one where every skein of wool has a place, every place is visible, and you can actually find what you are looking for without pulling the whole shelf apart. For anyone with a serious yarn collection, that is not a small thing. That is the difference between a stash that feels like chaos you are managing and a stash that feels like a collection you are curating.

If you try this project, I would love to hear how you customize it for your own setup. Everyone’s stash is different, and the nice thing about foam board is that it is endlessly adjustable. Cut something wrong, cut it again. Change your mind about the organization system, pull out the dividers and reconfigure. The whole thing costs less than ten dollars and takes less than an hour, and the payoff is a craft space that finally looks as organized on the inside as you have always wanted it to be.