Explosion Box: Size, Steps and What Goes in Each Layer

An explosion box looks like a plain cube until you lift the lid. Then the four sides fall flat and a stack of small layers is waiting inside: photos, notes, little pockets, a hidden drawer. It’s the paper gift people keep, and it’s built from a few squares of cardstock and a lot of scoring.

I’ve made these for birthdays and an anniversary, and the first one I folded went wrong in the same three places every beginner’s does. This post covers what an explosion box is, the size that works, how to build one step by step, what to put in every layer, and ideas by occasion.

What is an explosion box?

It’s a folded paper box in two parts: a base whose four sides are hinged to fall outward, and a lid that holds them upright. Inside, extra layers sit on top of the base. Each layer is the same footprint as the base with walls that get shorter as you go up, so every layer stays visible when the box opens.

The surprise is the point. It’s not a gift box you open once. It’s a small album you open again.

What you need to make an explosion box

• Cardstock: 65 to 80 lb. Thinner paper buckles on the walls, and heavier paper cracks on the fold.
• A ruler with a metal edge. You’ll measure a lot of 3-inch squares.
• A scoring tool: a bone folder and ruler, or a scoring board. Scoring before folding is what gives you a clean fold and no cracking.
• Adhesive: a double-sided tape runner for the walls, PVA glue for anything heavy.
• Scissors or a craft knife, and a cutting mat.
• Patterned paper for the outside and the layers.

The size to start with

Start at 3 inches (7.5 cm) square. It’s big enough to hold photos and small enough that a mistake costs you one sheet.

Part	Size
Base net (cross shape)	Centre 3 inches square, four flaps 3 inches each, so 9 x 9 overall
Lid	About 1/8 inch (3 mm) larger than the base, with walls about 1 inch tall
Layers	Same 3-inch footprint, each with shorter walls than the last
Paper for one box	A 12 x 12 sheet for the base, another for the lid and layers

How to make an explosion box step by step

1. Cut the base. Cut a 9-inch square. Score at 3 inches and at 6 inches in both directions, so you have a tic-tac-toe grid.
2. Remove the corners. Cut out the four corner squares so you’re left with a cross.
3. Fold the four flaps up along the scores to make a box with no lid. Test that it folds flat too.
4. Make the lid. Cut a piece a little bigger than the base, score walls about 1 inch, cut the corners, and glue the tabs. Check that it slides over the base without a fight.
5. Build the layers. Cut each layer with shorter walls than the last. Glue the layer in the middle of the base so its walls fold flat with the others.
6. Decorate before you glue. Cover the outside of the lid and the inside faces of the flaps with patterned paper while they’re still flat.
7. Add a ribbon to the lid so you can lift it, or a small tab.
8. Open it and shut it three times. If something catches, trim the flap, not the lid.

The three places a first one goes wrong

• Not scoring. Folding cardstock without a score cracks the paper on the outside of the fold.
• A lid that’s too tight. Paper adds thickness with every layer of patterned paper, so a lid cut to exact size won’t go on. That extra 1/8 inch is what saves it.
• Decorating after assembly. Once a box is glued, the inside faces are hard to reach. Decorate first.

What to put in each layer

The base is for the biggest thing: a photo, a card or a folded letter. Then work up in size order.

• Layer one, the big one: a photo on card, or a folded note.
• Layer two, pockets: a pocket for a small item, a ticket, or a folded message.
• Layer three, a pull-out: a strip on a tab, to pull up and read.
• Top layer, the reveal: a small charm, a sweet, or the one line you most want them to read.
• Under the base: a hidden drawer or a tuck for a gift card or note.

Explosion box ideas by occasion

• Birthday: one photo per year across the layers, with a wish on the top layer.
• Anniversary: photos in date order, tickets from a shared trip, one line per year.
• Wedding or engagement: a small photo set and a message from each guest.
• Graduation: one layer per school year, and the ceremony photo on the top.
• Baby or new home: a pocket for a card and a scan of the first picture.
• Valentine’s Day: a tiny note for each reason, folded into pockets.
• Christmas: a small treat in each layer, opened one at a time.

Cutting by hand or by machine

Everything above can be done with a ruler and a craft knife. A cutting machine helps in two places: making the layers identical, and cutting decorative edges.

• By hand: best for a first box. You’ll learn the folds.
• By machine: best if you’ll make several. A cutting file gives you scores and cuts in one pass.
• Free files: usually licensed for personal use, so read the line before making boxes to sell.

If you have a cutting machine and want to try several box shapes, a bundle of 3D box templates gives you cut and score lines ready to go, so you can skip the measuring.

Key takeaways

• An explosion box is a lidded box whose walls fall flat to show layered pages inside.
• Start with a 3-inch (7.5 cm) base cut from a 9-inch square of 65 to 80 lb cardstock.
• Score every fold before you fold it.
• Make the lid about 1/8 inch (3 mm) bigger than the base.
• Decorate the inside faces while the pieces are flat.
• Use free templates for personal projects and check the licence before selling.

Next pages to try: junk journal ideas, paper crafts and templates and mini albums and paper projects.