I built my first custom board game insert in 2019 and watched it pancake into a heap of cards within a month of vertical storage. The walls were too thin, the joints were weak, and gravity won every time.
Designing a board game insert that survives being stored on its side comes down to three things: understanding the forces at play, choosing the right materials, and applying basic structural engineering principles. Get all three right and your insert will hold up for years of vertical storage on a packed shelf.
After building 14 custom inserts for my own collection over the past three years and testing every common failure mode, I’ve settled on a repeatable process. I’ll walk you through the engineering principles, material choices, and bracing techniques that actually work when the box spends more time on its side than flat.
The short answer: A vertical-storage insert uses thicker walls, reinforced corners, and diagonal bracing to channel gravitational loads into the box itself. When the insert is slightly compressed against the lid and the walls form a triangulated structure, the whole assembly behaves like a rigid unit instead of collapsing under its own weight.
Table of Contents
Why Vertical Storage Breaks Most Inserts?
Most insert designs assume horizontal storage. The components sit on top of the walls, gravity presses straight down, and nothing is trying to twist or shear the structure apart.
Flip that box on its side and everything changes. The components now push against the walls laterally. The walls that were vertical are now horizontal and have to support the full weight of all the components above them. The walls that were supporting weight are now free-floating and can buckle outward.
I tested this with a simple Spirit Island insert that worked perfectly flat. Two months of vertical storage and the long token wall bowed outward by 4mm, letting all the small pieces migrate into the card compartment. The cards got scratched by fear tokens within a week.
The three forces that destroy inserts in vertical storage are compression (walls crushing under weight), shear (joints sliding apart), and torsion (the whole insert twisting inside the box). A good design addresses all three.
Vertical storage also exposes weak glue joints. In horizontal storage, gravity holds everything together. In vertical storage, every joint is under tension, and a poorly glued corner will pop open within weeks.
Core Structural Engineering Principles for Inserts
You don’t need an engineering degree to build a structurally sound insert, but you do need to think like one. Four principles cover 95% of the structural challenges you’ll face.
Load Distribution
Every component in your game exerts a downward force when stored vertically. The trick is distributing that force across as much structure as possible instead of letting it concentrate on single walls.
Think of your insert as a small building. Tall compartments are like tall buildings; they need wider bases and internal bracing to stay upright. Wide, shallow compartments are like foundations; they spread weight across a larger area.
In practice, this means putting heavier components (metal coins, miniatures, chunky tiles) in compartments closer to the box bottom. When the box is vertical, these heavy items are now near the wall, providing ballast that resists tipping.
Compression vs Tension
Foam core is strong in compression but weak in tension. Push down on a piece of foam core and it resists. Pull it apart and it tears easily.
This matters for joints. A butt joint (two pieces glued flat against each other) relies entirely on the glue for tensile strength. A rabbet joint (one piece slotted into another) uses mechanical structure to handle tension, with the glue just sealing the connection.
I use rabbet joints for every load-bearing connection in my inserts. They’re a bit more work but they hold up to vertical storage for years without failing.
Triangulation
Triangles are rigid. Rectangles are not. A square frame can rack into a parallelogram with almost no force. Add one diagonal brace and that same frame becomes rock solid.
For inserts, this means adding diagonal supports inside any compartment taller than 40mm. A simple diagonal piece from one corner to the opposite corner transforms a floppy wall into a structural beam.
Tight Fit as Structure
An insert that fits snugly inside the box becomes part of the box structure. The box walls brace the insert walls, and the lid presses down on top, creating a pre-loaded assembly.
An insert that wobbles inside the box relies entirely on its own structure and will fail much sooner. Aim for a fit where you have to press the insert into the box with light thumb pressure.
Material Selection for Vertical-Storage Inserts
Material choice has a bigger impact on vertical storage performance than any other design decision. The three main categories each have their strengths.
Foam Core Grades Compared
Foam core comes in three thicknesses that matter for inserts: 3mm, 5mm, and 10mm. Each has a place in your design.
3mm foam core is fine for internal dividers between compartments of similar size. It will not hold up as a load-bearing wall in vertical storage. Save it for non-structural partitions.
5mm foam core is the workhorse for most inserts. It cuts cleanly, glues well, and has enough rigidity for walls up to 60mm tall in vertical storage. I use 5mm for roughly 80% of my insert walls.
10mm foam core is overkill for most walls but invaluable for base plates and lid caps. The extra mass and rigidity make it perfect for components that take abuse, like miniature trays.
MDF (Medium-Density Fiberboard)
MDF is the premium choice for serious insert builders. It’s heavier, harder to cut, and produces dust that requires a mask, but it has exceptional vertical storage performance.
A 3mm MDF wall has more structural strength than a 5mm foam core wall. If you’re building an insert for a heavy game like Twilight Imperium or a game with lots of metal components, MDF is worth the extra effort.
The main downside is that MDF requires laser cutting or precision tools. Hand-cutting MDF is frustrating and the edges crumble.
Corrugated Plastic (Corflute)
Corrugated plastic is the budget hero of insert materials. It’s what real estate signs are made of, and it has surprisingly good structural properties for the price.
The flutes (those hollow channels inside the material) act like miniature I-beams, giving corflute excellent stiffness for its weight. A 4mm corflute wall performs comparably to a 5mm foam core wall.
The catch is that corflute wants to flex along the flute direction but is very stiff across it. Plan your cuts so the flutes run vertically in your walls.
Acrylic
Acrylic inserts look stunning but require laser cutting and specialized skills. For our purposes, acrylic is more relevant as a reference for what’s possible than as a practical DIY material.
If you want acrylic-level precision without the tools, consider a service like BoardGameInsertMaker or The Game Tamer. They laser-cut custom inserts that handle vertical storage as well as anything you could build yourself.
Measuring and Planning for a Tight, Stable Fit
Measurement errors are the most common cause of insert failure. A wall that’s 1mm too tall creates a gap; a wall that’s 1mm too short creates a wobble. Both cause problems in vertical storage.
Measure Twice, Cut Once (Really)
Measure every dimension of the box interior at three points: near each edge and in the middle. Boxes are not perfectly square, and a 2mm variation across a 300mm dimension is common.
Always use the smallest measurement for your cut. A slightly tight wall can be sanded to fit. A slightly loose wall cannot be fixed without starting over.
Account for Lid Pressure
The lid of a board game box typically sits 3-5mm above the box rim. This gap is where your insert’s top edges live, and the lid presses down on them when the box is closed.
Design your insert so the top edges of the walls sit 1-2mm below the lid’s bottom surface. This gives you the pre-loading effect that turns the insert into structural part of the box assembly.
Draw It Out First
Before cutting anything, draw the insert layout to scale on graph paper. I use 1 square = 5mm for most games. This forces you to think through component placement and brace placement before committing to cuts.
Mark which walls are load-bearing and which are just dividers. Then plan your bracing for the load-bearing walls specifically.
Cutting Techniques That Prevent Crumbling
Foam core wants to crumble. The paper facing tears, the foam core compresses unevenly, and before you know it your clean cuts look like they’ve been through a garbage disposal. Proper technique solves this.
The Multiple Pass Method
Never try to cut through foam core in a single pass. The blade drags through the foam, compressing it and leaving a ragged edge.
Instead, make three light passes. The first scores the paper facing. The second cuts through the foam. The third cleans up the opposite paper facing. This produces edges sharp enough to look laser-cut.
Blade Selection
A fresh #11 blade is non-negotiable for foam core work. Dull blades crush instead of cut, and you’ll fight the material the entire time.
Change your blade after every 8-10 cuts. Sounds excessive, but a sharp blade is the difference between a 20-minute build and a 3-hour frustration.
Score and Snap for Long Cuts
For cuts longer than 100mm, score and snap is faster and more accurate than multiple passes. Use a straightedge and lightly score the paper facing on one side, then snap the piece over the edge of your cutting mat.
Score and snap works best for cuts that will be hidden inside the assembly. For visible cuts, multiple passes produce cleaner results.
Assembly and Gluing for Vertical Stability
Glue selection and joint design determine whether your insert survives its first vertical season or falls apart within weeks.
Hot Glue vs Alternatives
Hot glue is the standard for foam core inserts. It sets fast, bonds well to paper facing, and has enough flex to absorb minor shocks without cracking.
The main disadvantage is that hot glue can warp thin foam core if you apply too much. Use a thin bead, not a thick rope, and apply it in short bursts so you can position pieces before the glue sets.
PVA (white) glue creates stronger bonds but takes 30+ minutes to set. It’s worth using for any joint that will see significant stress in vertical storage. I use a 50/50 mix approach: PVA for major structural joints, hot glue for partitions and quick assembly.
The Joint Sequence
Assembly order matters. Build the base plate first, then add walls in a sequence that lets each wall brace the previous one.
Start with opposite walls (front and back, or left and right) to keep the assembly square. Then add the remaining walls. Finally, install internal partitions and bracing.
Dry-fit every piece before gluing. Foam core joints don’t forgive mistakes, and a misaligned wall during glue-up means starting over.
Reinforcing Critical Joints
For inserts that will see heavy vertical storage, I reinforce the four corners of the base plate with small triangular gussets. These can be scrap foam core cut into 20mm right triangles.
The gussets spread the corner load across a larger glue surface, dramatically improving joint strength. My 14 inserts all have gusseted corners, and none have failed at the base in three years.
Advanced Bracing Techniques for Heavy Components
Basic insert construction handles light games fine. But when you’ve got miniatures, metal coins, or chunky wooden pieces, you need advanced bracing to keep everything in place during vertical storage.
Corner Bracing
The weakest points in any insert are the corners. They’re where walls meet, where forces concentrate, and where glue joints see the most stress.
For heavy games, I add internal corner braces: small L-shaped pieces that fit inside each corner and extend 30-40mm up each wall. These effectively double the wall thickness at the highest-stress point.
Diagonal Supports
Any compartment taller than 50mm that holds heavy components needs diagonal bracing. This is the triangulation principle in action.
For token compartments, a simple diagonal strip from the bottom front corner to the top back corner is enough. This single piece of foam core transforms a floppy wall into a structural panel.
For miniature compartments, use two crossing diagonals forming an X. This handles forces from any direction, which matters when the box gets jostled during transport.
Base Plate Reinforcement
The base plate takes the most abuse in vertical storage. All the weight of all the components presses on it, and if it flexes, the whole insert shifts.
For heavy games, use a double base plate: two layers of 5mm foam core glued together. The 10mm total thickness resists flex far better than a single layer.
For really heavy games like Gloomhaven, consider using 10mm foam core for the base plate from the start. The extra thickness pays for itself in long-term stability.
Lid Cap Design
The lid cap is a flat piece that sits on top of your insert, creating a finished surface that the box lid presses against. It’s also your last line of defense against component migration.
For vertical storage, the lid cap should be slightly compressed when the box is closed. This pre-loads the entire assembly and prevents components from shifting when the box is moved.
Cut the lid cap 1-2mm taller than the available space. When you close the lid, it presses down firmly on the cap, locking everything in place.
How to Test Insert Stability Before Final Assembly?
There’s nothing worse than gluing everything together only to discover a structural problem. Build testing into your workflow from the start.
The Dry Fit Test
After cutting all pieces but before any gluing, dry-fit the entire assembly in the box. Every wall should sit flush, every partition should align, and the whole insert should press into the box with light thumb pressure.
If anything wobbles or gaps, fix it now. Glue amplifies every error.
The Shake Test
With the dry-fitted insert in the box, shake the box vigorously in all directions. Listen for any rattling or movement. Watch for walls shifting.
If you hear components rattling inside compartments, your walls are too short or your dividers are misaligned. If walls shift, your corner joints need reinforcement.
The Vertical Drop Test
Set the box on its side on a table, then lift it 10cm and set it back down. Do this 10 times on each side. Any weakness will show up within these 40 drops.
This test catches weak glue joints, insufficient bracing, and poor fit. If the insert survives this, it will survive normal shelf life.
Iterate With Cardboard First
For complex inserts, build a cardboard prototype first. Cardboard cuts fast, costs almost nothing, and lets you iterate on layout without wasting foam core.
I built three cardboard prototypes for my Mage Knight insert before committing to foam core. The cardboard version took 30 minutes and saved me hours of foam core rework.
Common Mistakes and How to Avoid Them
I’ve made every mistake in the book. Here are the four that cause the most failures.
First, pillar gaps at the bottom of walls. Foam core walls need to sit on a base plate, not next to it. A wall that’s glued to the side of the base plate will eventually separate because the glue joint sees all the vertical load.
Second, weak glue joints from insufficient surface area. A 5mm bead of hot glue does not have much bonding surface. For structural joints, rough up the surfaces first with sandpaper to give the glue more to grip.
Third, forgetting the lid gap. Measure from the inside bottom of the box to the inside top of the lid, not just to the rim. Insert walls that touch the lid will prevent the box from closing.
Fourth, underestimating weight. A few hundred grams of components feels light in your hands, but it’s a significant load on thin foam core walls. When in doubt, upgrade to thicker material or add bracing.
Frequently Asked Questions
Can I store board games sideways?
Yes, you can store board games sideways, and vertical storage actually saves significant shelf space. The key is using an insert that fits snugly and has reinforced walls to handle the lateral forces. Without a proper insert, components can shift and damage each other.
Is it better to store board games vertically or horizontally?
Vertical storage is better for most collections because it saves space and makes games easier to access on a shelf. Horizontal storage puts less stress on inserts but wastes vertical space. The main risk of vertical storage is insert collapse, which proper structural design prevents.
What are the disadvantages of using foamcore?
The main disadvantages of foamcore are its weakness in tension, tendency to crumble when cut improperly, and limited load-bearing capacity for heavy components. Foamcore also degrades over time if exposed to moisture. For heavy games, consider MDF or corrugated plastic instead.
How to stick foam core together?
Stick foam core together using hot glue for quick assembly or PVA white glue for stronger structural joints. Apply glue in a thin bead, press pieces together firmly, and hold for 30 seconds. For load-bearing joints, rough up the surfaces with sandpaper first to improve adhesion.
How to design a 3D printed board game insert?
Design a 3D printed board game insert using CAD software like Tinkercad or Fusion 360, focusing on the same structural principles as foam core: thick walls, corner bracing, and tight fit. 3D printing allows for custom compartments and integrated features like card holders, but requires access to a printer.
Final Thoughts
Designing a board game insert that survives vertical storage isn’t complicated, but it does require thinking about forces, materials, and structure from the start. Follow the principles in this guide and your inserts will hold up for years.
Start with your heaviest game, build a cardboard prototype, and apply the bracing techniques we’ve covered. Once you’ve got one insert right, the next ones get easier and faster. Your collection will thank you.